Wild card Alison Riske ousts ailing Petra Kvitova to advance at U.S. Open

Alison Riske, 23, joins fellow Americans Serena Williams and Sloane Stephens in the fourth round. (Alex Trautwig/Getty Images) NEW YORK -- The 2013 U.S. Open

Alison Riske, 23, joins fellow Americans Serena Williams and Sloane Stephens in the fourth round. (Alex Trautwig/Getty Images)

NEW YORK -- The 2013 U.S. Open is all about firsts for 23-year-old Alison Riske. The American wild card knocked out 2011 Wimbledon champion Petra Kvitova 6-3, 6-0 on Saturday to advance to the fourth round of a Grand Slam tournament for the first time. Riske produced a composed performance in her first victory against a top-10 player, though the seventh-seeded Kvitova was struggling with a virus that had kept her in bed Friday.

"I had a fever, so I didn't come to the site yesterday," Kvitova told reporters. "So unfortunately I tried to play, tried to fight. But, yeah, my body wouldn't let me to fight."

Before the U.S. summer hard-court season, Riske was known for being more of a grass-court specialist. Just two months ago, she was ranked outside the top 150. But a strong grass-court season, in which she made the semifinals at Birmingham and the third round at Wimbledon, boosted her back toward the top 100. Still, expectations were low for Riske on the hard courts, where she had yet to win a WTA-level main-draw match.

She finally broke that streak in July, when she defeated Vania King at the Citi Open in Washington, D.C. She got another win at the New Haven Open, where she lost to Kvitova in three sets in the next round. With that positive momentum, she began this week by recording her first career U.S. Open victory and has now defeated two seeds (No. 28 Mona Barthel along with Kvitova) to get into the second week. She's done it in convincing style, too, not dropping a set in three matches.

"It's just really cool because I feel like I'm playing within myself," Riske said. "I'm not doing anything crazy. It just feels really comfortable. It's exciting."

Her career-best run here is a form of vindication for Riske, a Pittsburgh native. An ebullient personality (you should really follow her on Twitter @Riske4Rewards) who counts Melanie Oudin as her best friend on tour, she actually intended to skip turning pro to play college tennis for Vanderbilt in 2009. A financial backer stepped in and she turned pro two weeks before classes were set to begin. Toiling away mostly on the ITF circuit, Riske took four years to finally crack the top 100. She admits that there were doubts about whether she could cut it on the pro tour.

"It's really tough out here," she said. "Every week isn't like this.  But that's the great part about it, too, because if you do have a bad week you can kind of follow it up the following week with something better."

Riske joins Serena Williams and Sloane Stephens in the fourth round and she adds her name to the growing list of younger American women making waves this year. That group includes Stephens, Jamie Hampton, Madison Keys and Christina McHale, who looked poised to join Riske in the fourth round when she served for the match against Ana Ivanovic on Saturday, only to lose 4-6, 7-5, 6-4. They've inspired each other to make a collective push up the rankings, snagging some big wins in the process.

"When everybody else wins, you're like, 'Oh, gosh, I wish I could be doing that, too,''' Riske said. "But I think that's why it is great, because it shows you that I hit with them, I practice with them, I can do it too."