Rotterdam World Cup 2023

Jan Groenendijk - John Stins 2-0 (2023)

After 21-26? Groenendijk won a piece using the standard combination 17.27-21! 26x37 18.32x41! 23x43 19.21x14 9x20 20.49x38

Devanand Orie - Martijn van IJzendoorn 0-2 (2023)

Van IJzendoorn demonstrated why the move 8.34-29? is quite dangerous here. 14-20 9.50-44 10-14 10.38-32(?)

Here the paradoxical move ≡ 10.40-34?! was a much better way to defend the outpost on 24. The justification for this move is 14-19 11.28-23! 19x28 12.38-32 and most of the problems for white are gone.

≡ 4-10 11.37-31(?) 21-27! 12.32x21 16x27 13.42-38?

Now the game is over. The best defense was probably ≡ 13.42-37 14-19 14.40-35 19x30 15.35x24 27-32 16.39-34 32x23 17.29x27 20x38 18.43x32 with a very unbalanced position for white.

≡ 14-19! 14.40-35 19x30 15.35x24 27-32!

With this standard maneuver black wins a piece. Sometimes this is only temporary, but in this case white has no chance to win it back.

16.38x18 12x34 17.39x30 20x38 18.43x32 25x34 19.48-43 17-21 20.26x17 and black won the game.

Wouter Sipma - Jan van den Hooff 2-0 (2023)

34.33-29!?

Sipma successfully speculates on a combination. On Toernooibase Martin Dolfing mentions that ≡ 34.33-28 was the best move in this position. An important variant is 15-20 35.38-33 20-24 36.43-39 11-17 37.42-38 17-22 38.28x17 21x12 39.33-28 12-17 40.38-33 8-12 41.48-42 3-9 42.42-38. Now the logical move 9-14? loses after 43.34-30 17-21 44.47-41 12-17 45.41-36 and we have reached the famous position Ricou - Bonnard (with the colors swapped). But with ≡ 17-21! black can make a draw.

≡ 11-17? 35.37-31! 26x28 36.27-22 18x27 37.29x9

and black didn't await 3x14 38.38-33 28x30 39.35x2.

Kariem Droog - Jitse Slump 0-2 (2023)

White was already a bit in trouble due to the lack of control on the left wing. But after 23.33-28? 22x33 24.38x29 19-24!! the game was suddenly over. White cannot defend the piece on 29 with 25.43-38 24x33 26.38x29 due to the combination 14-19 27.25x23 12-18 28.23x21 16x47. And after ≡ 25.32-27 24x33 there is no way for white to capture the lost piece back.

Renco Oostindjer - Simon Harmsma 0-2 (2023)

After 46.34-30? Harmsma surprised his opponent with the piece sacrifice 33-39! 47.43x34 20-25! 48.40-35 28-33?

This move is very logical, but the computer shows that this enables white to escape using 49.27-21! 18-22 and now the unexpected double sacrifice 50.30-24!! 19x39 51.45-40. The correct move was ≡ 2-7.

≡ 49.48-42? 2-7!

This move seals the victory for black.

50.27-21 18-22 51.42-37 33-38 52.37-32 38x27 53.21x32 7-12 54.45-40 12-18

Danny Staal - Dirk van Schaik Sr. 2-0 (2023)

After 38.47-42! it looked like the game is over. Van Schaik decided to sacrifice a piece with 22-27 and lost the game. But black could have rescued the game with the combination ≡ 24-30! 39.35x2 22-27! 40.2x32 28x48 41.31-27 15-20 etc.

Victor Foss - Sytze Spijker 0-2 (2023)

After 47.37-31? Spijker missed a golden opportunity to win the game: 35-40! 48.31-26 40x29 49.26x17 29-34!! and the white position is completely lost.

Tom Swelsen - Gerard Peroti 2-0 (2023)

Instead of 26.33-29? Swelsen should have played ≡ 26.34-30! Then the black left wing is immobilized. And after 21-26 27.42-37 11-17 white has the combination 28.25-20 14x34 29.40x29 23x34 30.28-22 17x39 31.38-33 39x28 32.32x5.

Harry Clasquin - Jos Stokkel 0-2 (2023)

After 33.40-34? Stokkel decided the game with the combination 22-27! 34.32x23 19x28 35.33x22 24-30 36.35x24 14-20 37.25x14 9x49 38.38-33 49-43

Matheo Boxum - Yulia Bintsarovska 2-0 (2023)

Boxum tricked his opponent with an unusual combination after 17-22? 23.31-26! 22-28 24.26x17!! 28x30 25.33-28 12x21 26.29-24! 30x19 27.28-23 19x28 28.32x1

Mark Werrebrouck - Gerard Peroti 2-0 (2023)

After 12-17? Werrebrouck could have created big problems for his opponent by blocking the left wing using 33.31-26! 8-12 34.36-31! 3-8 35.45-40. Now black must advance to the sixth row with 24-29 36.33x24 20x29 37.39-33 29-34 38.40x29 23x34. This looks completely lost after 39.35-30, but the computer is able to make a draw using the miraculous defense 18-22 40.27x20 15x35 41.43-39 34x43 42.48x39 19-24! 43.39-34 12-18! Despite the piece advantage this appears to result in no more than a draw. 44.31-27 8-12 45.27-21 16x27 46.32x21 18-22 47.28-23 24-30 48.23-18 30x28 49.18x7

Janes de Vries - Arie van Diggele 2-0 (2023)

14-20? Van Diggele could have successfully attacked the outpost on 24 using ≡ 14-19! 16.40-35 19x30 17.35x24 9-14! Now 18.45-40? loses due to the combination 15-20! 19.24x15 4-10 20.15x4 17-22! 21.4x27 21x45 B+. Hence ≡ 18.49-44 14-19 19.45-40 19x30 20.40-35 5-10 21.35x24 10-14. Since 22.44-40? loses due to the exact same combination, white loses a piece after ≡ 22.38-33 14-19 23.44-40 19x30 24.40-35 4-9 25.35x24 9-14 26.29-23 13-18! 27.33-29 18-22 28.46-41 22x33 29.29x38 7-11! etc.

Menno Kamminga - Juan Camelia 0-2 (2023)

Kamminga didn't sense the danger after 8.39-33? 17-22! 9.28x17 14-19 10.25x23 21-27 11.31x22 12x21 12.23x12 8x50 13.29x20 15x24 and Camelia won the game.

Arjan van Leeuwen - Bert Dollekamp 1-1 (2023)

When Van Leeuwen sacrificed a piece with 59.32-27 31x22 60.16-11 he probably didn't believe that he could win the game anymore. But it turns out that the endgame after ≡ 59.16-11 31-36 60.11-7 36-41 61.7-1 18-22 is actually winning after 62.24-20! 41-47 63.20-15! 47-33 64.1-40! (and not ≡ 65.15-10? 33-39! or ≡ 65.1-7 33-39! 66.15-10 39-48!! with in both cases a draw) ≡ 33-39 65.40-7! Now black must give up the strategic square 39, which gives white the opportunity to make a second king using 39-33 66.15-10 W+

Maarten Wichgers - Leo van Vlerken 2-0 (2023)

After 29.45-40? Van Vlerken missed the break through combination 21-27 30.31x22 13-18! 31.22x13 8x28 32.33x22 12-18 33.22x13 14-19 34.13x24 20x29 35.34x23 25x45 B+

Ratan Ganeshie - Robert van Diggele 1-1 (2023)

Van Diggele failed to punish the mistake 12.30-25? with the combination 18-22! 13.25x14 22x33 14.38x18 13x22! 15.14x23 12-18 16.23x21 16x47 B+

Matheo Boxum - Simon Harmsma 0-2 (2023)

After 31.31-26? Harmsma decided the game with a very nice forcing: 11-17! 32.22x11 16x7! 33.28-22 (since ≡ 33.38-32? loses after 25-30 34.34x23 3-8 35.29x20 18x47 B+) ≡ 12-17! 34.22x2 18-23 35.29x18 13x31 36.26x37 19-23 37.2x30 23-29 and white resigned.

Wim Kalis - Luise Gabbert 2-0 (2023)

After 18-23? Kalis won using a standard maneuver in this game type: 24.27-22! 17x28 25.26x17 11x22 26.33-29! 23x34 27.32x23 19x28 28.39x10 4x15 29.38-32 and the outpost on 28 could not be defended.

Renco Oostindjer - Anton van Berkel 0-2 (2023)

Oostindjer didn't spot the hidden combination that Van Berkel had prepared for him: 33.42-37? 18-22! 34.28x17 8-12 35.17x8 23-28 36.32x14 20x9 37.8x30 25x41

Harry Clasquin - Gijs Schoenmakers 0-2 (2023)

The black piece on 9 is outplaced, and after 6-11(?) 40.40-34 11-17? (here the exchange ≡ 23-29 41.34x23 18x29 was necessary) ≡ 41.34-30! white had a winning advantage. 17-21 42.36-31 12-17 43.39-34?

Clasquin chooses the wrong plan. But winning this position turns out to be difficult in practice. It appears 7 times in the database, but so far nobody was able to play it correctly. Christian van der Schaaf came very close in a game in 1991 against former world champion Shchegolev (with the colors swapped) ≡ 23-29! 40.34x23 18x29 41.27-22 12-18! 42.28-23 19x39 43.30x8 18x27! and now Schchegolev decided to bluff with 44.38-33?!? That worked well, since Van der Schaaf accepted a draw. Probably he had calculated the variant 29x47? 45.8-3 27x38 46.37-31 26x37 47.3x50 with a draw. But with ≡ 27x47! 45.33x15 39-44 black could have won the game.

≡ 17-22 44.28x17 21x12 and later it was black who won the game.

Katarzyna Stanczuk - Yulia Bintsarovska 0-2 (2023)

After 34.38-32? Bintsarovska decided the game with 23-29! 35.34x14 9x20 36.30x19 25-30 37.35x24 20x47

Pertap Malahé - Bé Eggens 2-0 (2023)

Both players missed the combination for white after 3-8? Now instead of 31.37-31? white should have played ≡ 31.27-21 16x27 32.33-28 23x34 33.40x9 13x4 34.37-31 26x37 35.42x2 W+

Ad de Hoon - Peter van der Stap 0-2 (2023)

After 36.39-34? Van der Stap made use of the white piece on 15 in an original way: 25-30! 37.34x25 24-29 38.15x33 14-20 39.25x14 13-19 40.14x23 18x49 and white resigned.

Janes de Vries - Ratan Ganeshie 0-2 (2023)

In order to make a draw, white has to chase both black kings from the main diagonal. After 57.24-20? 23-19! this was no longer possible. The right move was ≡ 57.38-33! and now for example 23-5 58.24-19 5x16 59.47-41 46x50 60.15-10 with a draw.

Simon Harmsma - Jan Groenendijk 0-2 (2023)

Most likely Harmsma felt pretty comfortable about his position after 29.43-38!? Admittedly, the white right wing is very heavy, but after for example 17-21 30.28-22! 9-14 31.49-44 it is black who needs to worry most. Moreover, the logical move ≡ 2-7? is forbidden due to the nice combination 30.34-30 25x23 31.28x19 20x29 32.32-28 13x24 33.28-22 17x28 34.27-21 16x27 35.38-32 27x38 36.42x11 W+. But Groenendijk had looked deeper and won the game with a spectacular combination: ≡ 16-21! 30.27x16 17-22 31.28x17 12x21 32.16x27 18-23 33.29x18 13x31 34.37x26 20x29 35.34x23 25-30! 36.35x24 15-20 37.24x15 5-10 38.15x13 8x48 39.38-33 48-25 40.26-21 3-8 41.40-35

Alexei Ovsyanko - Leo van Vlerken 1-1 (2023)

After 52.34-30? Van Vlerken was able to make a draw using 17-21! 53.28-22 12-18 54.30-25 18-23 55.24-20 23-29 56.20x18 29-33 57.18-12 33-38 58.32x43 21x41 etc. Ovsyanko could have won the game using ≡ 52.28-22! 17x28 53.32x23 and now for example 16-21 54.27x16 13-18 55.34-29 18-22 56.24-19 14-20 57.19-13 22-27 58.13-9 etc.

Harold Jagram - Mehmet Yöney 0-2 (2023)

In this position Jagram missed the spectacular combination 31.34-29 23x25 32.28-23 19x37 33.38-33 21x32 34.43-38 32x43 35.48x39 37x48 36.39-34 48x30 37.35x2.

Ratan Ganeshie - Dirk van Schaik Sr. 1-1 (2023)

Instead of 3-9? Van Schaik could have forced a win using ≡ 19-24 38.43-38 24x33 39.38x29 13-19! 40.42-38 or? 20-25! and white cannot play 41.40-35 due to 25-30 42.35x22 17x46 43.29x18 B+

Matthijs Broek - Johan Evens 1-1 (2023)

Here 53.38-32? was the wrong way to make a capture position. Broek could have won the game using ≡ 53.39-33! 26-31 54.46-28! 31-36 55.28-46! etc. W+

Frans Teijn - Bas Baksoellah 2-0 (2023)

In this defensive position Baksoellah lost the game after 13-18? 49.32-28! etc. With the unexpected ≡ 26-31! 48.37x26 (since ≡ 48.27x36? 12-18! 49.23x21 16x38 with a draw) ≡ 12-18!! 49.23x21 14-19! he could have made a draw.

Peter van der Stap - Rob Geurtsen 0-2 (2023)

Here Geurtsen played the inaccurate move 2-7?, but Van der Stap failed to take advantage of it with the alert response 12.37-31! Then 22-28? is of course prohibited, and ≡ 21-26? loses a piece after 13.47-41 26x37 14.41x21 11-16 15.35-30 16x27 16.29-23 19x28 17.30-24 20x29 18.34x21. This means that black has to close the position with something like ≡ 7-12 13.31-26 12-17, but this is a positional disaster for black.

Peter van der Stap - Rob Geurtsen 0-2 (2023)

4-9?

Black should have played ≡ 17-21! 47.28-22 23-28 48.22x13 28x30 49.25x34 19x8 with a winning advantage.

≡ 47.35-30?

The players do not know their classics. With ≡ 47.34-30! 9-13 48.36-31! 17-21 49.28-22!! white could have made a draw. For example 23-28 50.32x23 21x41 51.22-17 19x39 52.17x10 26x37 53.30x19 and this endgame is a draw.

≡ 24x35 48.33-29 26-31 49.37x26 35-40 50.34x45 23x34 51.27-21 16x27 52.32x21 18-22 53.38-33 34-39 54.33x44

Darya Tkachenko - Guido van den Berg 2-0 (2023)

After 29.49-43? Van den Berg missed a very good opportunity with 24-29! 30.33x24 20x29 Then white has to choose between (1) 31.48-42 11-17 32.42-37 19-24! 33.28x30 17-22 34.34x12 22x44 35.40x49 8x17 36.32-28 21-27! and (2) ≡ 31.39-33 21-26 32.33x24 19x39 33.28x19 13x24 34.43x34 26-31 35.27-21 16x27 36.32x21 31-37. In both cases white is in a lot of trouble.

Matheo Boxum - Alexei Ovsyanko 2-0 (2023)

When he played 14-19? Ovsyanko may have had the illusion that he could successfully attack the white outpost on 24. But Boxum quickly pulled him out of his dream using the combination 33.34-30! 25x23 34.33-29! 23x34 35.40x29 19x30 36.37-31 26x37 37.38-32 37x28 38.39-33 28x39 39.43x5 and white won the game.

Devanand Orie - Tanya-Marie Cnossen 1-1 (2023)

The white left wing is under a lot of pressure. 28.49-44?

The only defense was ≡ 28.45-40. Then after 17-22 29.28x17 11x31 30.36x27 24-29 31.33x24 20x29 white has the exchange 32.40-34! 29x40 33.35x44.

≡ 17-22! 29.28x17 11x31 30.36x27 6-11?

But this is too slow. The right way to proceed the attack was ≡ 24-29! 31.33x24 20x29. Then 32.39-33? isn't possible due to 23-28 33.32x12 21x41 34.33x24 19x30 35.35x24 13-18 36.12x23 41-46 B+ Also ≡ 32.35-30? doesn't work due to 29-34! 33.30-25 23-28 34.32x12 21x41 35.39x30 41-47 and white cannot make a king due to 36.12-7 19-24! 37.30x8 3x1. Finally, after ≡ 32.44-40? 6-11 white has no defense against the attack 11-17 followed by 17-22.

Luise Gabbert - Eddy Fuzzally 1-1 (2023)

In this position Fuzzally panicked with 16-21? and lost the game. With the cold-blooded ≡ 23-29! black could have made a draw, since 43.28-23? 19x28 44.30x17 doesn't work due to 18-22! 45.32x34 22x44.

Wouter Sipma - Jan Groenendijk 0-2 (2023)

In the eighth round Sipma and Groenendijk played a very interesting game. 9-14!?

With this very risky move Groenendijk does an ultimate attempt to win the game. The piece on 14 is hanging, and it is not clear how to develop this piece later on. In the game Groenendijk will be successful, but this move could easily have backfired on him. A more conservative plan was ≡ 7-12 37.48-43 2-7 38.27-21 16x27 39.32x21 23x32 40.38x27 19-23 with an equal position.

≡ 38.27-22 14-20 39.48-42

On Toernooibase the grandmasters Boomstra, Dolfing and Heusdens conclude that white could probably have won the game here. Boomstra gives the following long variant as a proof: ≡ 39.50-44 30-35 40.48-42 24-30 41.33-29 8-12 42.29x18 12x23 43.38-33 2-8 44.33-29 8-12 45.29x18 12x23 46.42-38 19-24 47.28x19 24x13 48.38-33 20-24 49.34-29 7-12 50.29x20 25x14 51.22-17 12x21 52.26x17 13-18 53.33-29 14-19 54.32-28 19-24 55.29x20 30-34 56.39x30 35x15 57.28-23 18x29 58.17-12 29-33 59.12-7 1x12 60.6-1 12-17 61.1-6 W+

≡ 8-13 40.22-17 13-18 41.17-12(?)

Here ≡ 41.17-11! looks very strong, but Dolfing notes that this leads to a draw after 30-35 42.50-44 16-21 43.26x17 7x16 44.28-22 18x27 45.32x21 16x27 46.33-29 24x33 47.38x18 27-31.

≡ 30-35 42.50-44 24-30 43.34-29?

Sipma makes a tactical mistake. After ≡ 43.42-37 20-24! it is white who needs to make a draw. But this is certainly possible, for example 44.28-22 18x27 45.32x21 16x27 46.37-32 7x18 47.32x21 18-22 48.21-17 22x11 49.6x17 23-28 50.33x22 19-23 51.38-33 23-28 52.44-40 35x44 53.39x50 30x39 54.33x44 28-32 55.22-18 etc.

≡ 23x43 44.12x14 20x9 45.38x49 30-34 46.33-29 34x23 47.28x19 25-30! 48.44-40 35x44 49.49x40 30-34!

This is the combination that Sipma must have overlooked.

50.40x29 16-21 51.26x17 7-12 52.17x8 2x33 53.32-27 33-39 54.27-21 39-44 55.21-17 9-13 56.17-11 44-50 57.42-38 13-18 58.38-32 50-22

Zhuoyuan Du - Martijn van IJzendoorn 0-2 (2023)

The unknown Chinese player Du played a very good tournament. After 13-18? he could even have won against the strong Dutch grandmaster Van IJzendoorn using the combination 35.38-33! 50x28 36.32-27! 28x46 37.34-29 23x34 38.42-37 46x49 39.48-42 49x21 40.16x11 W+

Emre Hageman - Erik Hoogendoorn 2-0 (2023)

After 9-13? Hageman decided the game with a couple of powerful moves: 38.33-28! 24-30

Also losing is ≡ 7-11 39.43-38 8-12 40.42-37 15-20 (or ≡ 11-16 41.38-33! 15-20 42.40-35 W+) ≡ 41.39-33 24-30 42.40-35 30x39 43.33x44 20-24 44.44-39 11-16 45.39-34! etc.

≡ 39.43-38!

Now after 7-12? 40.40-35 black has no waiting move, and thus effectively the game is over.

≡ 15-20 40.27-22 18x27 41.32x1 23x43 42.39x48 30x39 43.1-6

Juan Camelia - Iwan Fung 2-0 (2023)

After the logical 24-29? Camelia won beautifully using 46.28-23! 19x28 47.27-21! 17x37 48.48-42 37x39 49.40-34 39x30 50.35x2