The Chess Mind

It's a good thing he did, too, as the other two games were quick, dull draws. Ivanchuk and Cheparinov went at it hammer and tongs in a Classical King's Indian with 9.Ne1 Nd7 10.Nd3 f5 11.Bd2. It's a slightly old-fashioned line with tons of theory, but it's still lots of fun seeing if White's queenside breakthrough will come before Black delivers checkmate. Ivanchuk played a novelty on move 25, though it was his opponent's reply that probably constituted the more significant new idea. In any case, the position remained in a complicated balance for a long time, but starting at move 32 Cheparinov - possibly in time trouble, despite the 24 "free" moves - lost the thread (maybe the whole spool) and resigned on move 40 about to be a rook down.

There's plenty of time left, but things look good for Ivanchuk at this point:

Standings after Round 4:

1. Ivanchuk 4
2. Topalov 2.5
3-5. Radjabov, Aronian, Cheparinov 1.5
6. Bu Xiangzhi 1

Round 5 Pairings:

Topalov - Bu Xiangzhi
Aronian - Ivanchuk
Cheparinov - Radjabov

Tournament site here, the games with my comments here.