The loss proved quite expensive for Anand as he lost the joint lead and was relegated to third spot in the US$ 1 million prize money event being played on a double round robin basis among eight players.
On another eventful day, when every game produced a result, Veselin Topalov of Bulgaria made most of his opportunities to grind down Michael Adams of England, emerging as the sole leader with 3.5 points from four games.
As a matter of fact, had the Bulgarian not squandered a strong position against Anand in round two, his scoreline would have read an awesome 4/4, something almost unheard of in elite chess circles against such extraordinary opposition in recent times.
Russian Peter Svidler made sure Topalov did not get a runaway lead in this 14-round contest, with his second straight victory in the event. The modest Russian was a bit lucky to beat compatriot Alexander Morozevich in a topsy-turvy game.
Also ending on the winning side was Peter Leko who had it easy against Judit Polgar, his Hungarian compatriot.
With Topalov in command, Svidler took his tally to 3 points out of a possible four, with Anand at sole third with 2.5 points.
Kasimdzhanov improved his situation after beating Anand to stand sole fourth on 2 points while the Hungarian duo of Judit Polgar and Peter Leko are next in line with 1.5 points apiece. Alexander Morozevich and Adams are currently at the bottom of the tables on one point.
For Anand it turned out to be a bad day at the office when nothing worked right. The Indian started off with the Nazdorf variation and faced the English attack wherein Kasimdzhanov got the imbalance he was looking for given his situation in the event prior to this game.
The Uzbek, the lowest ranked player in the tournament, got an advantage in the middle game when Anand went for an erroneous plan and slowly built his attack against a slightly weakened king of the Indian, reaping rich dividends. Anand fell prey to some brilliant combative ideas in the end and gave in when he was just a move away from getting checkmated.
Topalov, considered Anand's main rival here, continued with his demolition act and recorded another swift victory.
Michael Adams, for the second day running, fell prey to some fine tactics well complemented with excellent calculations.
The middle game arising out of an English symmetrical offered little hope for the Englishman as Topalov first seized the bishop pair with uncompromising play and later found a big hole in Adams' calculation on the 35th move.
Morozevich is the other player struggling to make an impact here and was yet again tested by Svidler who came on top from a position arising out of a King's Indian defence.
Morozevich had done well in the middle game but was outplayed in the ensuing heavy pieces endgame. He blundered towards the end to net a lost position.
Peter Leko eventually showed his mettle against Polgar in another Sicilian of the day. Going for the kill right from the beginning of this 25-move encounter, Leko made sure he did everything right and Polgar had little chance in the middle game to make any real impact.
Results round 4:
Peter Leko (Hun, 1.5) beat Judit Polgar (Hun, 1.5); Rustam Kasimdzhanov (Uzb, 2) beat Viswanathan Anand (Ind, 2.5);Veselin Topalov (Bul, 3.5) beat Michael Adams (Eng, 1); Alexander Morozevich (Rus, 1) lost to Peter Svidler (Rus, 3).
Pairings round 5 (to be played on Sunday):
Adams-Kasimdzhanov; Anand-Leko; Polgar-Morozevich; Svidler-Topalov
The moves:
Rustam Kasimdzhanov v/s V Anand
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 Ng4 7. Bg5 h6 8. Bh4 g5 9. Bg3 Bg7 10. h3 Ne5 11. Nf5 Bxf5 12. exf5 Nbc6 13. Nd5 e6 14. fxe6 fxe6 15. Ne3 O-O 16. Be2 Qe7 17. O-O Rad8 18. Bh5 Kh8 19. Re1 d5 20. a4 Nc4 21. Nxc4 dxc4 22. Qg4 Qb4 23. Qxe6 Rd2 24. Rad1 Nd4 25. Qe4 Nf5 26. Be5 Rxf2 27. Bf3 Rd2 28. Bxg7+ Kxg7 29. Qe5+ Rf6 30. a5 Nh4 31. Qc7+ Rf7 32. Qe5+ Rf6 33. Bh5 Ng6 34. Bxg6 Rxd1 35. Rxd1 Kxg6 36. Qe4+ Kg7 37. Rd7+ Kg8 38. Qh7+ black resigned.
