Two-time finalist John Isner kept his big serve humming winning his sixth straight match beating 2014 finalist Vasek Pospisil 6-4, 7-6 in a match that concluded around 1:30am.
Isner will now face Ricardas Berankis tonight in a rematch of their Atlanta quarter.
No. 2 seed Kei Nishikori won over Leonardo Mayer 6-4, 6-4. No. 3 Marin Cilic edged Sam Querrey in two breakers.
“I’ve had good preparation with my coaches coming into this week and I hope to do well,” said Nishikori who now plays Australian big server Sam Groth. “I’ve never played [Groth] before, and it’s never easy to play big servers, but I am serving and returning well, so I’ll just have to take the small chances I get.”
Grigor Dimitrov continued to struggle, falling in three sets to Steve Johnson 6-3, 1-6, 6-3. Dimitrov then pulled out of the doubles with Mardy Fish citing a shoulder injury.
Johnson’s countryman Jack Sock picked up an excellent win coming back to beat Wimbledon semifinalist Richard Gasquet 6-7(4), 7-6(5), 6-4. Sock will now play Johnson tonight.
“It should be a good battle. We’ve played a few times now and each won a couple and last time we played was last year’s French Open,” said Sock. “He’s playing some pretty good tennis now, he’s had some pretty consistent results and moved up the rankings. I think especially on a surface like this and in the U.S., both playing here, it should be a fun match. I’m just happy there’s two Americans advancing.”
And 18-year-old Alexander Zverev continued to show his future promise beating Alexandr Dolgopolov 2-6, 6-2, 6-4.
“It’s a big tournament for me, being here in the quarterfinals,” said Zverev. “Honestly, I only played on a hard court for the first time on Saturday, coming off of clay. So winning such big matches and beating such good players is an unbelievable feeling for me.”
Zverev will now face US Open champion Cilic today.
The women’s event today features Sam Stosur and Sloane Stephens who faces fellow American and 19-year-old Louisa Chirico.
In Kitzbuhel, Philipp Kohlschreiber just ended Dominic Thiem’s 10 match win streak beating the home Austrian 6-0, 7-6 to advance to the clay final. And in that final tomorrow he’ll face Paul-Henri Mathieu who beat Nicolas Almagro.
In Stanford, while former finalists Agnieszka Radwanska and Angelique Kerber advance setting up a quarterfinal showdown today, top seed Caroline Wozniacki was hobbled by a left calf injury in a 6-4, 6-2 loss in her tournament debut match.
I’m not 100 percent, but I still thought I could tough it out, play and still win,” Wozniacki said. “But it’s the first match back after a long break and everything’s fast. It didn’t really give me a chance to get a rhythm. It wasn’t pretty out there, that’s for sure.”
Wozniacki first injured the calf during the grass season.
FRIDAY WASHINGTON SCHEDULE
STADIUM COURT start 1:00 pm
ATP – S. Groth (AUS) vs  K. Nishikori (JPN)
Not Before 3:00 pm
ATP – A. Zverev (GER) vs  M. Cilic (CRO)
ATP – R. Berankis (LTU) vs  J. Isner (USA)
ATP –  J. Sock (USA) vs S. Johnson (USA)
You Might Like:
Grigor Dimitrov Hit Another Spectacular Shot Last Night In Washington [Video]
Andy Murray Shocked In Washington Opener, Madison Keys Crashes Out Of Stanford
Caroline Wozniacki, Angelique Kerber Pull Out Of Events; Venus Williams Wins In Stanford Opener
2011 Tennis-X Top-American-Not-Named-Williams Standings: Week 2
Serena Returns Tonight In Stanford; Berdych, Raonic, Isner Begin In Washington