American Jack Sock beat Jiri Vesely of the Czech Republic 6-2, 6-1 on Wednesday in the U.S. National Indoor Tennis Championships to advance to his second quarterfinal this year.
Sock needed 68 minutes to top Vesely at The Racquet Club, overcoming six double-faults.
Michael Russell also advanced, beating fellow American Tim Smyczek 6-2, 7-6 (5). Russell will play third-seeded Lleyton Hewitt of Australia or Marcos Baghdatis of Cyprus.
Defending champion Kei Nishikori of Japan is scheduled to play his first match Wednesday night against Benjamin Becker of Germany. This is the first time Nishikori has been the top seed at an ATP Tour event. He's trying to defend his first title.
Qualifier Denis Kudla beat fellow American Donald Young 6-1 6-1 in a first-round match needing only an hour to get a little payback for losing to Young here last year.