American Riske Upsets Kvitova at U.S. Open as Azarenka Wins

American wild-card invitee Alison Riske upset seventh-seeded Petra Kvitova at the U.S. Open to reach the fourth round of a Grand Slam tournament for the first time, while No. 2 Victoria Azarenka needed three sets to advance.

No. 2 men’s seed Rafael Nadal of Spain cruised past Ivan Dodig of Croatia in straight sets at the National Tennis Center in New York, where Christina McHale almost became the second U.S. woman today to beat a former major winner, serving for the match before falling to Ana Ivanovic of Serbia.

Riske, 23, who was born in Pittsburgh and trains in College Park, Maryland, beat Kvitova 6-3, 6-0. Ranked 81st on the WTA Tour, Riske was invited to play the event after failing to qualify on her own. She won 85 percent of her first serves and had seven unforced errors, compared to 27 for her Czech opponent, the Wimbledon champion in 2011.

“It was really emotional for me,” Riske told reporters. “I feel like I’m playing within myself. I’m not doing anything crazy and it feels really comfortable, so it’s exciting.”

Kvitova, 23, said after the match she had a high fever yesterday and was diagnosed with a virus, hampering her performance.

“My body didn’t help me today,” she told reporters. “I tried to play, I tried to fight, but my body wouldn’t let me.”

Riske next will play Daniela Hantuchova of Slovakia, who overcame four match points to beat Israeli qualifier Julia Glushko 3-6, 7-5, 7-6 (7-4).

Azarenka, the two-time defending Australian Open winner and 2012 U.S. Open runner-up, dropped a first-set tiebreaker to Alize Cornet of France before pulling out the match 6-7 (2-7), 6-3, 6-2.

Slow Start

Azarenka made 20 unforced errors in the opening set, compared to 11 in the second and seven in the third.

“The first set Alize played really well and I wasn’t patient enough,” she said in an on-court interview after her match. “I had a lot of chances and I didn’t convert them.”

Azarenka next meets 13th-seeded Ivanovic after the 2008 French Open winner came from behind to beat McHale.

McHale, a 21-year-old ranked 114th on the WTA Tour, was leading 6-4, 5-4 with a chance to serve out the match for her first trip to a Grand Slam fourth round. Instead, her serve was broken by Ivanovic, who took the set 7-5 and won the final set 6-4.

“I couldn’t find my rhythm in the beginning so I just tried to keep my head down and tried to be aggressive,” Ivanovic said in an on-court interview after the match in Arthur Ashe Stadium. “It paid off, so I’m very pleased.”

Nadal’s 18-0

Nadal, whose 12 Grand Slam championships include the 2010 U.S. Open title, extended his undefeated record on hard courts this year to 18-0 with a 6-4, 6-3, 6-3 defeat of Dodig on the Ashe court.

The 27-year-old Nadal, who missed the 2012 tournament with a knee injury, won points on 80 percent of his first serves and 74 percent of his second serves, not allowing a break.

“I started the match with the right intensity,” Nadal said in a televised on-court interview after advancing. “I think I played my best match this year.”

Nadal’s fourth-round opponent will be 22nd-seeded Philipp Kohlschreiber of Germany, who won in four sets today against American John Isner, the No. 13 seed.

It’s a cloudy day in Flushing Meadows, Queens, and there’s a 50 percent chance of rain this afternoon and tonight, according to the National Weather Service.

Ferrer Advances

Men’s No. 4 seed David Ferrer of Spain topped qualifier Mikhail Kukushin of Kazakhstan and No. 10 Milos Raonic of Canada beat 23rd-seeded Feliciano Lopez of Spain. No. 18 seed Janko Tipsarevic of Serbia defeated unseeded American Jack Sock in four sets.

The losses by Sock and Isner left Tim Smyczek, a wild-card entrant ranked 109th in the world, as the only American man left in the tournament.

Caroline Wozniacki, the 2009 U.S. Open runner-up from Denmark, plays Italian qualifier Camila Giorgi to open evening play in Arthur Ashe Stadium. That match will be followed by Roger Federer of Switzerland, the five-time U.S. Open champion whose 66-8 record at the tournament gives him the best winning percentage (.892) among men, taking on Adrian Mannarino of France.

Federer’s No. 7 seeding is his lowest for the tournament since 2002. The 32-year-old has not dropped a set to Mannarino in two previous meetings.

Before it's here, it's on the Bloomberg Terminal.