Canadian second seed Milos Raonic downed American Jack Sock to set up a third-round clash with Lleyton Hewitt at the Washington Open.
The Canadian ousted Sock 7-6 (7-3) 7-6 (7-3) on Wednesday, while Japanese fourth seed Kei Nishikori outlasted American Sam Querrey 6-4 5-7 6-4 and Steve Johnson downed countryman John Isner 6-7 (5-7) 6-3 7-6 (8-6).
Czech top seed Tomas Berdych, seeking his 10th career ATP title and first on US soil, defeated US qualifier Robby Ginepri 6-1 6-4 at the $US1.9 million ($A2 million) hardcourt tune-up for the US Open.
Raonic, who ended the run of Australia's Nick Kyrgios in the quarter-finals at Wimbledon before falling to Roger Federer in the semis, advanced to face the Australian veteran and 2004 Washington champion Hewitt on Thursday (Friday AEST).
"He's (Sock) gotten a lot of matches in this summer. I knew it was going to be a challenge for me today," Raonic said.
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"I'm happy that after getting down that break, I was able to come back.
"I created a lot of opportunities for myself, I just didn't make the most of them, and then just played two very solid tie-breaks."
Nishikori, seeking his sixth career title and third of the year, fired nine aces against 12 by Querrey in advancing after one hour and 52 minutes.
"I stayed solid from the baseline and concentrated on my service games," Nishikori said.
The 24-year-old Asian star, ranked 11th, next faces Slovakian Lukas Lacko with French sixth seed Richard Gasquet a potential quarter-final foe.
