Grandmaster Wesley So lost with the white pieces twice to France’s Maxime Vachier-Lagrave and dropped the first of two four-game quarterfinal matches, 3-1, in the Airthings Masters of the Champions Chess Tour Wednesday.
The 27-year-old So yielded to the Sicilian Defense of Vachier-Lagrave in the second and fourth games while drawing the first and third games in a pair of Ruy Lopez games that allowed his French rival to gain the upper hand.
So, who came into the quarters as the second seed after a solid, undefeated performance in the preliminaries, will need to take the final mini match set Thursday to knot their duel and force a deciding tiebreak showdown.
So is looking at replicating his triumphant effort in the Skilling Open where he shocked world champion Magnus Carlsen to snatch the crown a month ago.
The winner of the So-Vachier-Lagrave duel will advance the semis against the winner between Levon Aronian of Armenia and Hikaru Nakamura of the United States.
Aronian leads their match, 2.5-1.5.
In the other bracket, Carlsen is fighting Russian Daniil Dubov to a 2-2 deadlock while Azeri Teimour Radjabov and Russian Ian Nepomniactchi are clashing to break a 2-2 split.
More results at championschesstour.com.