American GM Wesley So (2760) won the tiebreak against Dutch GM Anish Giri (2798) to win the Bilbao Chess Masters, 2015.
Earlier during the day, both the games of Round 6 viz., Ding-Anand and So-Giri ended in draws, forcing a tiebreak match of blitz games to decide the winner among the Dutch and the American grandmasters.
In the first blitz game, Anish Giri built a winning position with the black pieces after So made some suspicious moves in a Queen’s Gambit Declined middlegame. Despite, being a pawn up, Giri failed to convert, and allowed So to fight back. Eventually, Giri ended up blundering a full piece, losing the game. In the second game, playing the white pieces, Giri again had a better position, but So defended hard. After several moves of back and forth, they both agreed to a draw in an opposite-coloured bishop ending.
GM Wesley So won the tie-break match 1.5-0.5, thus winning the tournament.