Williams, whose previous best in Tokyo was the quarterfinals in 2004, broke Bouchard with a forehand down the line to go up 5-2 in the third set and held on to win the match that lasted three hours at Ariake Colosseum.
Williams will face Petra Kvitova in the semifinals. The seventh-seeded Czech beat Svetlana Kuznetsova, 6-4, 6-1.
Also, fourth-seeded Caroline Wozniacki beat Lucie Safarova of the Czech Republic, 2-6, 6-3, 6-2, to set up a semifinal with fifth-seeded Angelique Kerber of Germany, who ousted second-seeded Agnieszka Radwanska of Poland, 6-4, 6-4.
Torres had the operation Thursday and General Manager
Torres was injured in a collision with Ducks forward
Lindsay Whalen and
Tiffany Hayes scored 23 points, Angel McCoughtry had 18 and the host