MANILA, Philippines – Chinese GM Li Chao stopped Wesley So’s win run at four with a big victory in ninth round with the Filipino GM dropping to a three-way tie in the Corus Group B Chess Championship at the de Morianne Community Center in Wijk Aan Zee, The Netherlands Tuesday.

So struggled to keep Li in check in the opening stages of the sharp line of the Gruenfeld defense before resigning under threat of mate on the 34th.

The 17-year-old Filipino champion, who wrested the solo lead on a four-game winning streak, failed to foil Li’s mate threat at the back rank, forcing him to give up.

Chess analyst Glenn Bordonada said So’s game went astray with 21. Nb5 instead of d6 – and took a turn for the worse with 22. Qa3 instead of Qc2.

His 27. dxc6 was also dubious compared to 27. Rd3, although white’s position remained difficult at this stage.

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,” So told his friends and supporters in Facebook hours after the game.

The loss, however, kept So in the lead although he now shares it with GM Gabriel Sargissian of Armenia, who outduelled top seed GM Zadek Wojtaszek of Poland, and GM Luke McShane of England, who halved the point with GM Jon Ludvig Hammer of Norway.  

The three have six points, half a point ahead of GM Zahar Efimenko of Ukraine and GM Vlad Tkachiev of France heading to the 10th round Wednesday.