Grandmaster Wesley So’s four-game winning streak ended Tuesday with a crucial ninth-round loss to Chinese GM Li Chao in the 73rd Tata Steel-Corus Group B chess championship at the de Morianne Community Center in Wijk Aan Zee, The Netherlands.

(After nine rounds)

6.0 points – L. McShane (England)
G. Sargissian (Armenia)
Wesley So (Philippines)

5.5 points – Z. Efimenko (Ukraine)
V. Tkachiev (France)

5.0 points – L. Chao (China)
D. Navara (Czech Republic)
R. Wojtaszek (Poland)

4.5 points– L. Q. Liem (Vietnam)

3.5 points – L. Fressinet (France)

3.0 points – S. Ganguly (India)
J. Hammer (Norway)
F. Nijboer (Netherlands)

2.0 points – W. Spoelman (Netherlands)

So’s (ELO 2673) shocking defeat to the lower-ranked but hard-fighting Li (2649) allowed GMs Gabriel Sargissian of Armenia and Luke McShane of England to climb up for a share of the top spot with the Filipino chess champion.

All three players have six points each, with four rounds left in this prestigious 14-player, category 17 tournament. They hold a 0.5 point lead over GMs Zahar Efimenko of Ukraine and Vlad Tkachiev of France going into Wednesday’s 10th round.

Sargissian joined So on top of the standings after beating top seed GM Zadek Wojtaszek of Poland while McShane, who was the solo leader after seven rounds, halved the point with GM Jon Ludvig Hammer of Norway.

So, handling white for the second time in the tournament, kept Li in check in the opening stages of a Gruenfeld defense before resigning under threat of mate after 34 moves.

The 17-year-old So had no clear answer about the setback.

“Forget about the commentary. I don’t really know why (I lost). I just need to rest,” he told friends and supporters on Facebook after the game.

So’s next opponent is Tkachiev, who is on a three-game roll after beating Hammer, Efimenko and GM Surya Ganguly of India.

The Moscow-born Tkachiev, a noted blitz player, moved to Kazakhstan with his family when he was eight years old and later settled in Cannes, France. He achieved his GM norm in 1996 and became France’s national champion in 2006 after a tiebreak match with GM Laurent Fressinet.

After Tkachiev, So’s remaining opponents are GM Friso Nijboer of Netherlands, McShane, and Wojtaszek for the final round. – JVP, KY, GMANews.TV