China's Wang Qiang failed to reach the U.S. Open semifinal as she lost to six-time champion Serena Williams in two sets, 0-6 and 1-6, in 44 minutes at Flushing Meadows on Tuesday.

This was Wang's maiden Grand Slam quarterfinal as she previously defeated second seed Ashleigh Barty of Australia in straight sets to reach the stage.

Williams' 100th win at U.S. Open

Williams, who was celebrating her 100th victory at her home slam, said: "Wow. It's really unbelievable from when I first started here at 16. I never thought I would get to 100."

"It never crossed my mind I would still be here. I love coming out in front of you guys and I never want to let it go.

"When I play someone who is playing well, I have to step up or go home. And I'm not ready to go, so I knew I needed to come out tonight and play well. I'm feeling good, had a really tough year and I'm still here."

"Physically I'm feeling great, and more importantly I'm having fun every time I come out here."

"Speaking of I grew up watching the U.S. Open and trying to get here. It is the first place where I won one of my 23 Grand Slams, so it is always something special to come out on this court."

On her semifinal opponent Elina Svitolina, Williams said: "She has had a great year, made the semifinals at Wimbledon and I feel like she wants to go one further, so I have to come out again and play well. I'm ready and happy."

Ukrainian fifth seed Svitolina won the chance to meet Williams as she exited British number one Johanna Konta in two sets, 6-4 and 6-4.

Medvedev keeps winning

In men's singles, Daniil Medvedev of Russia is continuing his hard-court roll right into the semifinals after beating Stan Wawrinka of Switzerland 7-6 (6), 6-3, 3-6, 6-1.

The No. 5 seed reached the final four at a major tournament for the first time and improved his tour-leading total to 49 victories this year. He reached the final in three straight tournaments on hard courts leading into the U.S. Open, winning the last one.

Medvedev, 23, had his legs treated twice in the first set but played through the pain to become the youngest semifinalist at the U.S. Open since Novak Djokovic was also 23 in 2010.

Wawrinka eliminated the defending champion Djokovic in the fourth round but fell short of getting back to the semifinals for the first time since winning the 2016 U.S. Open title.

Dimitrov stuns Federer to reach semifinals

Roger Federer of Switzerland gave away a lead against a guy he'd never lost to and was beaten 3-6, 6-4, 3-6, 6-4, 6-2 by 78th-ranked Grigor Dimitrov of Bulgaria in the U.S. Open quarterfinals before a stunned crowd at Arthur Ashe Stadium.

The 38-year-old Federer took a rare-for-him medical timeout after the fourth set, leaving the court with a trainer. It was not immediately clear what might have been wrong with Federer, although he did appear to be flexing his back after some points.

When play resumed after a break of nearly 10 minutes, Federer's form never picked up. He finished with 61 unforced errors, 33 on the forehand side.

Federer had been 7-0 against Dimitrov, taking 16 of their previous 18 sets.

Federer would have been the oldest Grand Slam semifinalist since Jimmy Connors was 39 at Flushing Meadows in 1991. He also was trying to add to his totals of five U.S. Open championships and 20 major trophies in all.

Instead, Dimitrov advanced to his third major semifinal, first in New York. He will face No. 5 Daniil Medvedev on Friday.

(With input from AP)