The Chinese grandmaster Wang Hao was something of a regular on the world chess scene in 2010, but then disappeared last year. He's back now, and with a vengeance, as his first half total of four wins (and a loss to Magnus Carlsen) has him in a dominating first place, all the more so on the 3-1-0 scoring system in place at Biel. In round 4 he defeated Anish Giri, who had been leading after three rounds. The chief culprit was probably 15.g3, a TN (theoretical novelty) that was more like TNT that backfired. Despite the fairly symmetrical pawn structure that resulted a couple of moves later, and the exchanges of several pieces, it was always Black who enjoyed more space and more control, and Giri was ground down mercilessly.
In round 5 Wang Hao won again, this time against Viktor Bologan, who has unfortunately managed to build flawlessly on Morozevich's "perfect" score. Bologan's 10...Bc8 was rare and the sequence 10...Ba6-c8, 11...Ba6-c8, 12...Bf5-c8, 13...Bc8-a6 was pretty amusing; but as students of the Benko Gambit know it's in fact a pretty typical maneuver. On move 10 the bishop does little on a6 but get in the Ra8's way, and that's thanks to the pawn on e2. Richocheting the bishop to f5 induces e2-e4, and then the bishop can bounce back to a6 and from there go to d3. Thus White played 15.Nf3, and that covered d3 but allowed 15...Bc4. Now neither 16.Ra1 nor 16.a3 is pleasant, while 16.b3 is an outright error. So Wang Hao simply sacrificed the a-pawn to break in the center. (He was up a pawn anyway, and returning it broke the pressure and let him completely take over the initiative.)
After 22.e6 White enjoyed a very big advantage, and soon it was a winning one, but on move 28 he gave most of it away. 26.Nd3 would have won a piece, and 26.Re2 would have been fine if he had met 26...Nc6(!) 27.Nxc6 (not 27.Qxb6?? Nd4!) Qxc6 with 28.Re7! Instead, he played 28.Re6?, probably missing 28...Qa4! 29.Qxb6 Qd1+ 30.Bf1 Rxf4! Taking the rook allows an immediate perpetual, so Wang Hao had to play 31.Qxc5 and hope to win the game all over again. He did. 35...Ke6 was an error, as was 42...Qg4. In the end, Bologan even lost his bishop, but after 42...Qg4 there was already no saving the game.
Wang Hao was not the only player to go 2-0 in rounds 4 & 5; Hikaru Nakamura did so as well. In round 4, he "welcomed" Bologan to the tournament by defeating him in a long, exciting but not very cleanly played game and after winning that game with Black in a Queen's Gambit Accepted he defeated Etienne Bacrot with White. Bacrot has played well and successfully with White in the tournament, but with Black he has used the King's Indian in every game and been decisively outplayed each time. Bacrot's earlier King's Indians were in the Bayonet Attack, but Nakamura chose instead the Petrosian System.
Bacrot followed theory for a long time, but it's not clear that he was really in control in terms of his preparation. His 14...f5 (rather than the usual 14...Bh6) left the beaten track (although Garry Kasparov beat Vladimir Kramnik with that move in a rapid event back in 1995, but Bacrot deviated from that game a move later. The position after White's 20th move had occurred in six earlier games, with White scoring 100%. Only Nakamura's 22nd move was officially new, but it's unlikely that either player was still in preparation by then. Certainly Bacrot wouldn't have been, or he would have prepared a losing line! Nakamura's move was a very good one, and when Bacrot played 22...Nb8, fearing 22...Nc5 23.b6, the upshot was that he was a piece down for the rest of the game, as that knight would never again see the light of day.
It all came down to whether Black's kingside attack could break through. If not, then the joke-knight on b8 would cost him the game. Objectively, it seems that White was much better or winning, but the position was complicated enough for the players to miss something, and perhaps they did. After Nakamura's apparently erroneous 29.Qd2 (the engine prefers 29.Nxg3, 29.Nxg5 Qxg5 30.gxh3 and even 29.b6) Bacrot missed a spectacular resource: 29...hxg2 30.Kxg2 Nh3!!, which would have offered dangerous counterplay. Having missed his chance, White kept control and won.
The day before Bacrot drew with White against Carlsen in a Bogo-Indian (via the Keres-Indian), and Carlsen could only draw in round 5 with Giri in a 5.d3 Petroff. (Boooooooooo!) The good news for Carlsen is that he has his round 3 game with Bologan coming Sunday, and as the Morozevich/Bologan "team" ("Morozogan"? "Bolozevich"?) has gone 0-for-the tournament so far, he'll have good chances to get right back into the race for first.
Here are the standings at the halfway point, excluding tomorrow's make-up game:
1. Wang Hao 12
2-3. Nakamura, Giri 8
4. Carlsen 6 (out of 4 games)
5. Bacrot 4
6. Bologan 0
Round 6 Pairings:
Nakamura - Carlsen
Bacrot - Wang Hao
Giri - Bologan