MELBOURNE, Australia — Rafael Nadal moved into the fourth round of the Australian Open without dropping a set or showing any signs that a freak knee injury is bothering him.
Second-ranked Nadal had a 6-2, 6-4, 6-2 win early today over Lukas Lacko, the last qualifier in the draw, and next plays either Feliciano Lopez or Tampa resident John Isner.
Nadal, who won the 2009 Australian title but has gone out in the quarterfinals due to injuries in the past two years, felt a crack and then sharp pain in his right knee while sitting in a chair at his hotel over the weekend. Medical tests didn't show any serious damage, and he has had the knee heavily taped in his three matches since.
"The knee is fine. That's important thing," the 10-time major winner said. "The match was a really complete match, a really solid one.
"Very happy about my game. Being in fourth round without losing a set, it's fantastic news."
Nadal is on the same half of the draw as Roger Federer at a major for the first time since 2005. Federer, who has won four of his 16 Grand Slam titles in Australia, beat Ivo Karlovic 7-6 (8-6), 7-5, 6-3.
On the women's side, top-seeded Caroline Wozniacki continued her quest for a first major title with a 6-2, 6-2 win over Monica Niculescu. Wozniacki, who needs to reach the quarterfinals to have any chance of retaining the No. 1 ranking, wasted one match point and was broken when she was serving for the match, but broke back immediately to ensure she moved into the Round of 16.
Third-seeded Victoria Azarenka beat Mona Barthel 6-2, 6-4 in a match between champions of two warmup tournaments.
Azarenka, who beat four seeded players to win the Sydney International last week, has only lost eight games at Melbourne Park en route to the Round of 16. She next meets Iveta Benesova, who beat Russian qualifier Nina Bratchikova 6-1, 6-3.
Barthel was on a 10-match run in Australia after capturing her first title at the Hobart International last week as a qualifier.
Andy Roddick is already out of the tournament, retiring during his second-round match against Australian veteran Lleyton Hewitt on Thursday.
He needed a medical timeout after injuring his right hamstring in the second set and played 16 more games before retiring when Hewitt gained a 3-6, 6-3, 6-4 lead.
"It's a miserable, terrible thing being out there compromised like that," Roddick said.
The 29-year-old American knew he wouldn't be able to fool an opponent he was playing for the 14th time.
"He's a tough guy to play," said Roddick, now 7-7 against Hewitt for his career. "You can try to ham-and-egg it against a lot of guys, but he's really intelligent. He knew what was going on."
Defending champion Novak Djokovic, who won three of the four majors last year, kept getting better in his 6-3, 6-2, 6-1 win over Santiago Giraldo.