WESLEY So went on the offensive to put away GM Alexander Onischuk in 45 moves of an English Opening, Saturday in the fourth round of the 2017 United States Chess Championship.
This handed the Filipino grandmaster, who is currently attached to the US Chess Federation, his second win in four games when action ended at the Chess Club and Scholastic Center of Saint Louis in St. Louis, Missouri.
The 23-year-old So moved back into the solo lead with three points after three co-leaders, Hikaru Nakamura, Daniel Naroditsky and Yaroslav Zhereboukh drew with their respective rivals.
The three are behind So with 2.5 points.
Analysts believe So could have played another draw, but he avoided it with an h3 pawn move on the 26th.
It was a surprise move that allowed the white-playing So to attack the queenside with his rook and knight.
Onischuk quit when So penetrated the backrank and trapped the black king with his rook and bishop.
So, who earlier drew with world no. 3 Fabiano Caruana in 49 moves of a Ruy Lopez Opening in Round 3, will be facing Zherebukh in the fifth round.
Nakamura halved his point with GM Gata Kamsky in 30 moves of a Queen’s Pawn Game, while Naroditsky split his point with Ray Robson in 30 moves of a Sicilian Najdorf.
On the other hand, Zhereboukh needed only 16 moves to play Samuel Shankland to a draw in their English Opening games.
According to chess analyst Cristian Chirila, that game was “just like in his game against Shabalov.”
“Wesley decided to take his opponent out of popular theory early on and played the KIA (King’s Indian Attack),” said Chirila.