In other action, Stanislas Wawrinka ended Sam Querrey's run in five sets, Mikhail Youzhny booked a spot in the quarterfinals in a four-set win over Tommy Robredo, and Rafael Nadal concluded a late-night affair against compatriot Feliciano Lopez in straight sets.
On the women's side, two berths in the semifinals were on the line, and a pair of familiar faces stepped up and delivered.
Defending champion Kim Clijstersfaced down her sternest test of the tournament and passed with flying colors in a three-set win over No. 5 seed Samantha Stosur, 6-4, 5-7, 6-3.
Two-time US Open winner Venus Williams continued to display fine form, defeating 2010 French Open champion Francesca Schiavone in straight sets, 7-6(5), 6-4. Venus and Clijsters will meet in a blockbuster women's semifinal on Friday.