Against an opponent rated more than two hundred points higher, Cios reached a won king-and-pawn endgame — and then, with the full point there for the taking, let it slip. A study in how little room for error a winning pawn ending leaves.
White Maciej Cios1742 |
Black Uzeyir Ismayilov1979 |
Event DD Den Haag Open 2026 · Round 6 |
Result ½–½ |
Opening · Site · Date Sicilian, O’Kelly Variation (B28) · The Hague · 19 March 2026 | |
| Cios1 missed win · 5 inaccuracies · Weighted error2 0.66Ismayilov2 game-losing moves · 3 inaccuracies · Weighted error 0.73 | |
AnalysisFritz 20, Tactical Analysis, 30 seconds per move. Evaluations in pawns from White’s perspective; marks and assessments are Fritz’s.
☛ Tap any move — or any board — to open the interactive board. It pins to the top and follows along; ←/→ step, × closes it.
1. e4 c5 2. Nf3 a6 — The O’Kelly, a flexible Sicilian sideline that invites White to commit first.1 3. c3 d5 4. exd5 Qxd5 5. d4 e6 6. Be2 Nf6 7. O-O Be7 8. dxc5 Bxc5 9. Qxd5 — The queens come off before the middlegame has properly begun. Fritz rather fancied keeping them on with 9.Bf4 , but the trade suits a clean, technical day. 9… Nxd5 10. Nbd2 — White is a shade better.
10… O-O 11. Ne4 Be7 12. c4 Nf6 13. Nxf6+ Bxf6 14. Rb1 Nc6 15. b3 Rd8 16. Bb2 Bxb2 17. Rxb2 e5 18. Rd1 — The pieces come out, and the heavy pieces line up on the d-file — over the next few moves they all come off.
18… Bf5 19. Rbd2 f6 20. Rxd8+ Rxd8 21. Rxd8+ Nxd8 — The rooks are gone. A level minor-piece endgame, bishop and knight apiece.
22. Nd2 Kf8 23. Bf3 Ke7 24. Ne4 Bxe4 25. Bxe4 — The last minor pieces head for the door; if anything Black’s knight is the happier piece here.
25… h6 26. Bd5 Kd6 27. b4 Nc6 28. Bxc6 bxc6 — And now it is a pure king-and-pawn ending, dead level. White’s only winning try is to fix the queenside and manufacture a passed pawn.
29. a4 e4? — Black’s first slip. The committal pawn push hands White a winning position; 29…f5 kept the balance.
30. Kf1? — And White gives it straight back. The win lay in 30.f3 , prising open lines for the king; after the text it is level again.
30… Ke5? — Ismayilov returns the favour. Again 30…f5 held; the text lets White’s king and pawns advance.
31. Ke2 Kd4 — The king strides to d4.
32. b5! cxb5 33. cxb5 axb5 34. axb5 — The passed pawn is born: a protected passer on b5 and the more active king. White is winning, cleanly.
34… Kc5 35. Ke3 f5 36. Kf4 g6 — And here White had one precise win — and a careless near-win that turns out to be only a draw.
37. g4? — The decisive missed win. The clean path was 37.h4 .
The clean win. The key is 38.h5 — a deflection that drags the g6-pawn off its post, so that after 39.Kxf5 White’s king and f-pawn run unopposed. Fritz reads the whole line at +20.87, a full point. Instead 37.g4? let the win evaporate. Tap the moves to play it out on the board.
37… fxg4 38. Kxe4 Kxb5 — Now Black is a pawn up, and the position is only equal.
39. Ke5 Kc4 40. Kf6 Kd3 41. Kxg6 Ke2 42. Kh5 Kf3 43. Kh4 Kf4 44. h3 h5! 45. hxg4 hxg4 46. Kh5 Kf5 47. Kh4 Kf4 48. Kh5 — The pawns come off, and Black finds the precise hold. Even as Fritz murmurs that White “really could win this,” there is no win left.
In a king-and-pawn ending a single tempo is the whole game. White had the win in hand and the conversion needed one idea — the h4 deflection — that 37.g4 walked straight past. A half-point against a 1979 is a fine evening’s work; but it is the point that got away. Where the last game gave nothing back, this one gave back the win.
- On the O’Kelly Variation (Sicilian, B28): the early 2…a6, a flexible sideline named after the Belgian grandmaster Albéric O’Kelly de Galway; it keeps …e5 and …b5 in reserve and sidesteps the main lines.
- Weighted Error Value: Fritz’s accuracy measure — the average error per move, weighted by position and expressed in pawns. Lower is better, with 0.00 effectively flawless; it discounts slips made in already-decided positions.
Diagrams rendered from the game score · analysis: Fritz 20, Tactical Analysis, 30s/move · ECO B28 · DD Den Haag Open 2026 · Pieces: Merida by Armando Hernández Marroquín (GPLv2+)