Viswanathan Anand, the favourite in the Fide world championship, had a nervous day before scraping through to the fourth round. His match with Alexander Khalifman needed two games at the normal slow time-limit, then two games at 25 minutes a player, then two five-minute games before the first decisive encounter gave Anand victory. The line up for the last 16 is as follows:

Gelfand - Tkachiev

Azmaiparashvili - Krasenkov

Anand - Almasi

van Wely - Georgiev

Zvyagintsev - Dreyev

Rublevsky - Short

Shirov - Akopyan

Adams - Svidler

Short should stand a good chance against Rublevsky, a 23-year-old Russian whose current rating matches Short's, but who lacks experience at the highest level. The Adams-Svidler encounter, however, looks the most promising battle of the round. These two have produced some of the best chess of the event so far. Here is the game that gave Svidler his place among the last 16:

White: Peter Svidler

Black: Vladimir Epishin

1 e4 e6 23 Rc3 Rc8

2 d4 d5 24 Rfc1 Rc6

3 e5 Bf5 25 b4 Qb6

4 Nf3 e6 26 Qf4 Qc7

5 Be2 c5 27 a4 Ng6

6 Be3 cxd4 28 Qd2 Qxe5

7 Nxd4 Ne7 29 b5 axb5

8 Bg5 Qa5+ 30 axb5 Rb6

9 Nc3 Bg6 31 Nd3 Qd6

10 0-0 a6 32 Rc8+ Kd7

11 h4 h5 33 R1c7+ Qxc7

12 Bd3 Bxd3 34 Rxc7+ Kxc7

13 cxd3 Nbc6 35 Qc3+ Kd7

14 Nf3 Ng6 36 Nc5+ Kd6

15 d4 Be7 37 Nxb7+ Kd7

16 Bxe7 Ngxe7 38 Qc5 Rxb7

17 a3 Nf5 39 Qc6+ Ke7

18 g3 Qb6 40 Qxb7+ Kf6

19 Na4 Qa7 41 b6 d4

20 Nc5 Nfxd4 42 Qc7 d3

21 Rc1 Nxf3+ 43 Kf1 Ne5

22 Qxf3 Ne7 44 b7 resigns

Borrowing an opening idea from Nigel Short's repertoire, Svidler produced a novel interpretation with 12.Bd3 - apparently helping Black by exchanging his bad bishop - then recapturing with the c-pawn.

The idea was to discourage Black from castling K-side, where White has a ready-made attack thanks to the black pawn which had been lured to h5, but without castling Black could not get his rook into play to contest the c-file. The price White had to play for this, however, was to leave himself with a pawn on d4 that needed defending.

Svidler solved that problem by sacrificing it, then offering the e-pawn as well. The basic idea is well known from the Milner-Barry Gambit in the French Defence, but transplanting it to a Caro-Kann is highly unusual.

After 22...Nxe5 23.Qe2 Black would have faced the prospect of a powerful knight sacrifice on e6. As he played, he stayed just one pawn ahead and looked safe enough until 27.a4! increased the pressure. This time, he did take the e-pawn, but after 29.b5, his rook was forced away from c6 and the white rooks broke through down the open file. Black gave up his queen for two rooks, but the position of the rook on b6 proved fatal and Svidler won it with a neat combination.