Vasek Pospisil and doubles partner Jack Sock of the United States received a walkover to the third round of the Australian Open after the opposing side of Robin Haase and Fernando Verdasco withdrew prior to the start of Friday's match.

Pospisil was eliminated in the first round of the singles competition on Monday. He fell 7-6 (7-4), 3-6, 2-6, 4-6, to Gilles Simon of France.

Daniel Nestor and Radek Stepanek were to face Lukasz Kubot and Marcin Matkowski, however their second-round match was postponed due to rain.

Federer 1st to notch 300 Grand Slam match wins

Roger Federer was already a long way clear at the top of the list of men with the most wins in Grand Slam singles matches, so becoming the first to 300 wasn't a major distraction.

He reached the milestone at Rod Laver Arena, when he moved into the fourth round of the Australian Open with a 6-4, 3-6, 6-1, 6-4 victory over Grigor Dimitrov.

"It's very exciting, I must tell you," Federer said of his latest record, adding that reaching 1,000 wins in tour matches last year was also a cause for celebration. "It was a big deal for me.

"Not something I ever aimed for or looked for, but when it happens, it's very special. Yeah, you look deeper into it, I guess, where it's all happened and how. So it's very nice."

Williams, Djokovic advance

Defending champions and top-ranked Serena Williams and Novak Djokovic had night matches starting at the same time on nearby courts.

Six-time champion Serena Williams raced to a 6-1, 6-1 win in 45 minutes over 18-year-old Russian Daria Kasatkina on Rod Laver Arena. She will next play Margarita Gasparyan, who beat Yulia Putintseva 6-3, 6-4.

Djokovic needed only 25 minutes to win the first set against No. 28-seeded Andreas Seppi but had a tougher time in the next two, saving two set points in the tiebreaker before winning 6-1, 7-5, 7-6 (6) on Margaret Court Arena. After making way for Williams on the main court, he noted it was his first match on Melbourne Park's No. 2 court since it was renovated to include a roof.

Djokovic, a five-time Australian Open champion, continued a streak of reaching at least the fourth round at every major since the 2009 French Open. He was also particularly wary of a third-rounder against Seppi, who beat four-time champion Federer at the same stage here last year.

"I played a quality player who took out Federer last year here and who has been on the tour for many years," he said. "It was a great test. It was a physical match. I'm just glad I got through."

Milestone for Sharapova

Maria Sharapova advanced to the fourth round with a 6-1, 6-7 (5), 6-1 victory over Lauren Davis for her 600th tour-level match win.

"Wow. I've won 600 matches?" Sharapova asked, responding to a question in an on-court interview. "Is this like a friendly reminder that I'm getting old? Might be."

The 28-year-old, five-time major winner is playing her 13th Australian Open since 2003 so she knew what to expect when she lost concentration in the second set despite being up and break and 30-love.

"You know you're in a Grand Slam environment, third round and against an opponent you haven't played ... that's fired up and is not going to just give you the match and that's exactly what happened," she said. "I am quite happy that I was able to step up in the third set. That was very important."

The first set was over in 26 minutes, with Sharapova getting two service breaks and not facing a break point herself. She was broken twice in the second, when Davis came back hard and eventually won in the tiebreaker, despite conceding a key point after a 27-shot rally when she volleyed into the net, and covered her face with her hand.

Sharapova took a bathroom break before the third set and returned with more composure, making just five unforced errors and breaking Davis three times.

Nishikori in familiar territory 

Kei Nishikori had some trouble with his wrist, taking a medical timeout and losing the next set before recovering to reach the fourth round at the Australian Open with a 7-5, 2-6, 6-3, 6-4 win Friday over No. 26-seeded Guillermo Garcia-Lopez.

Nishikori reached the 2014 U.S. Open final and the quarterfinals at the Australian and French Opens in 2015 before withdrawing from his second-round match at Wimbledon with an injured left leg.

Returning to the fourth round at Melbourne Park for the fifth straight year was a confidence booster, and he said the right wrist "actually, it was OK."

"In the first set I was sore but after treatment I felt better," he said. "I tried to stay tough, concentrated again — I played better in last set."

There was a full house on Margaret Court Arena for the match, including a big section of Japanese supporters waving flags, while matches on uncovered outside courts were delayed because of rain.

No. 15 David Goffin beat No. 19 Dominic Thiem 6-1, 3-6, 7-6 (2), 7-5 — his first win against a top-20 player at a Grand Slam — to reach the fourth round in Melbourne for the first time.​