US Open: Rafael Nadal cruises into 4th round, Victoria Azarenka battles through

Rafael Nadal breezed into the fourth round of the US Open on Saturday, moving nearer a potential showdown with Roger Federer, while second seed Victoria Azarenka battled her way into the last 16.

Nadal, a 12-time Grand Slam champion who has won nine titles since returning in February from a seven-month injury layoff, stretched a career-best hardcourt win streak to 18 matches by beating Croatian Ivan Dodig, 6-4, 6-3, 6-3.

"I started the match with the right intensity," Nadal said. "I think I played my best match of the week so far."

Second-seeded Spaniard Nadal, who completed a career Grand Slam with his 2010 US Open crown, and Swiss star Roger Federer, in his lowest Grand Slam seeding since 2002 at seventh, have never played at the US Open but could meet in the quarter-finals.

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.

Nadal, who has not lost his serve in three matches, took command early and connected on 65 percent of his first serves and fired 37 winners in improving to 56-3 this year.

"I have to improve a little bit of everything to keep going in the second week," Nadal said. "To win matches if you are not playing your best, it's impossible."

Next for Nadal, who missed last year's Open due to injured knees, will be German 22nd seed Philipp Kohlschreiber, who ousted US 13th seed John Isner

"He has been having a great season," Kohlschreiber said. "But I will try my best."

With Isner's ouster, host-nation hopes fall upon wildcard Tim Smyczek, the last American man in the draw on the 10th anniversary year of Andy Roddick's US Open title, the most recent Grand Slam crown by a US man.

Two-time Australian Open champion Azarenka escaped an upset bid while Daniela Hantuchova saved four match points to advance, but Grand Slam winners Petra Kvitova and Svetlana Kuznetsova were ousted.

Azarenka, who lost to top seed Serena Williams in last year's final, outlasted French 26th seed Alize Cornet 6-7 (2/7), 6-3, 6-2.

Cornet denied Azarenka on 10 of 11 break chances in the first set, but could not hold on after dominating the tie-breaker.

"The first set Alize played really well and I made too many mistakes," said Azarenka.

"I wasn't patient and didn't convert my chances. In the second set I started to take advantage of my opportunities and that made the difference."

Next up for Azarenka will be Serbian 13th seed Ana Ivanovic, the 2008 French Open champion who rallied past Christina McHale 4-6, 7-5, 6-4 -- denying the American when she served for the match in the second set.

"I couldn't keep my rhythm early in the match. I tried to keep my head down, stay calm and keep playing aggressive," Ivanovic said.

Czech seventh seed Kvitova, the 2011 Wimbledon champion who was diagnosed with a virus Friday, made 27 unforced errors and seven double faults in losing to 81st-ranked US wildcard Alison Riske 6-3, 6-0.

"I was lying in the bed yesterday and I had a fever," Kvitova said. "My body didn't help me to move little bit. So unfortunately I tried to play, tried to fight, but my body wouldn't let me."

Riske next faces 48th-ranked Slovak Hantuchova, who struggled with a sore right shoulder but beat Israeli qualifier Julia Glushko 3-6, 7-5, 7-6 (7/4).

Russian 27th seed Kuznetsova, the 2004 US Open and 2009 French Open champion, made 35 unforced errors in losing 7-5, 6-1 to Italy's 83rd-ranked Flavia Pennetta, who had dropped 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.

"It was incredible," Halep said. "I played my best match ever."

Spanish fourth seed David Ferrer outlasted Russian-born Kazakh qualifier Mikhail Kukushkin 6-4, 6-3, 4-6, 6-4 to reach the last 16, where he will meet 18th-seeded Serb Janko Tipsarevic.

Canadian 10th seed Milos Raonic blasted 28 aces to defeat 23rd-seeded Spaniard Feliciano Lopez, 6-7 (4/7), 6-4, 6-3, 6-4, to book a fourth-round match with French eighth seed Richard Gasquet, who advanced when Russian Dmitry Tursonov retired down 6-3, 2-6, 6-4, 4-2.