Slam winners sent packing at US Open
Svetlana Kuznetsova of Russia plays against Flavia Pennetta of Italy during the 2013 US Open in New York on August 31, 2013. Kuznetsova, the 2004 US Open and 2009 French Open champion who missed last year's US Open with a right knee injury, made 35 unforced errors in losing 7-5, 6-1 to Pennetta, who had lost their five prior career matchups.
Czech seventh seed Kvitova, the 2011 Wimbledon champion who was reportedly hospitalized Friday, made 27 unforced errors and seven double faults to lose in only 65 minutes, falling to 81st-ranked US wildcard Alison Riske 6-3, 6-0.
"It's so awesome," said Riske, who lost to Kvitova last week in New Haven in their only prior meeting. "That (result) really helped me to just focus and play my game."
It's also Riske's first trip to the last 16 at a Grand Slam, where she will face either 48th-ranked Slovak Daniela Hantuchova or 128th-ranked Israeli qualifier Julia Glushko, and ensures a first-ever jump into the world top 60.
Russian 27th seed Kuznetsova, the 2004 US Open and 2009 French Open champion who missed last year's US Open with a right knee injury, made 35 unforced errors in losing 7-5, 6-1 to Italy's 83rd-ranked Flavia Pennetta, who had lost their five prior career matchups.
Pennetta, who also ousted Italian fourth seed Sara Errani, will next face Romania's Simona Halep.
Halep, who won her fourth title in the past three months last week at New Haven, breezed into the fourth round at a Grand Slam for the first time by ripping Russian 14th seed Maria Kirilenko 6-1, 6-0 in 51 minutes.
"I'm really happy that I played so good," Halep said. "It was incredible. I played my best match ever."
Kirilenko, the fiancee of Russian ice hockey star Alexander Ovechkin trying to match her best run in 11 US Open visits, was no match for 21st seed Halep, the only WTA player this year to win on grass, clay and hard court.
"I just believed in myself," Halep said. "I'm more confident and more aggressive on court. I want to take the pleasure from every moment."
Halep had missed events at Washington and Toronto with a lower back injury but returned at Cincinnati and downed France's Marion Bartoli in the Wimbledon champion's last career match.
Second-seeded Spaniard Nadal and Swiss star Federer, in his lowest Grand Slam seeding since 2002 at seventh, have never played each other on the Flushing Meadows hardcourts, but triumphs later would put them each in the round of 16 on a collision course for the last eight.
Nadal, a 12-time Grand Slam champion who has won nine titles this year after returning from a seven-month injury layoff in February, takes a 17-match hardcourt win streak into a third-round affair with 38th-ranked Croatian Ivan Dodig, who won their most recent match in 2011 at Montreal.
Federer, seeking his 17th Grand Slam title and sixth US Open crown, will face French left-hander Adrian Mannarino, who has never beaten a top-10 foe, in a night match at Arthur Ashe Stadium.
US 13th seed John Isner, who complained about fans cheering for flamboyant Frenchman Gael Monfils in a second-round victory, gets a chance to avenge a third-round US Open ouster last year when he meets German 22nd seed Philipp Kohlschreiber.
Britain's Daniel Evans, in his deepest Grand Slam run, tries to reach the last 16 against Spanish 19th seed Tommy Robredo. Evans would be the first qualifier in the US Open fourth round since Luxembourg's Gilles Muller in 2008.
Spanish fourth seed David Ferrer will meet Russian-born Kazakh qualifier Mikhail Kukushkin while French eighth seed Richard Gasquet faces Russia's 32nd-seeded Dmitry Tursunov, who has won five of their seven career matches and seeks his first trip to a Grand Slam fourth round since Wimbledon in 2006.