Roger Federer will look back on it and wonder, just as he did on court, why he just watched as Andreas Seppi went down the line and ended his streak of reaching the Australian Open semifinals for 11 consecutive years.

The 17-time Grand Slam champion was facing match point against Seppi for the first time in their 11 head-to-head meetings, and had control of the rally when he hit a deep forehand into the corner and followed it to the net.

The No. 46-ranked Seppi lunged to his right and stuck out his racket, more hopeful than confident, and guided the ball down the line. Federer let it go past, and glanced back to see it land inside the baseline, giving Seppi a 6-4, 7-6 (5), 4-6, 7-6 (5) win and a spot in the fourth round.

"The way he hits it you think, 'This can't possibly land in.' You kind of go and you're there and you're like, 'No, I'm going to let it go,'" the second-seeded Federer said. "As you're telling yourself that, you look behind you and you already know it's done."

Federer had reached the semifinals or better at Melbourne Park ever since winning the first of his four Australian titles in 2004. He hadn't been ousted before the fourth round here since 2001. That changed in an instant.

"I don't know. Ask him how he felt hitting it," Federer said. "It's clearly a big blow because I actually hit my forehand pretty good."

Seppi was euphoric, but acknowledged that the defining shot of the match was not a calculated winner.

"Yeah, was for sure a strange shot," the 30-year-old Italian said. "At the beginning I thought I couldn't even reach the ball. Then, when I hit it, I didn't see it going there. I just saw when it bounced in.

"Was for sure one of the important shots of my life."

Seppi had only advanced beyond the second round once at his nine previous trips to the Australian Open. He held his nerve despite some withering winners from Federer, who registered his 1,000th career match win earlier this month in Brisbane. Federer, uncharacteristically, let mini-breaks slip in both tiebreakers, had nine double-faults in the match and was unusually inconsistent.

"It just broke me to lose that second set. And actually the fourth, I should win it, too," Federer said. "Just a brutal couple of sets to lose there. The end wasn't pretty."

Seppi will get another appearance on Rod Laver Arena for his fourth-round match against Australian teenager Nick Kyrgios, who shrugged off concern over a nosebleed to beat Malek Jaziri of Tunisia 6-3, 7-6 (6), 6-1. Kyrgios beat then No. 1-ranked Rafael Nadal in the fourth round at Wimbledon last year.

Nadal is still a contender in Australia after rebounding from his five-set, second-round win to beat No. 106-ranked Dudi Sella 6-1, 6-0, 7-5.

The 14-time major winner is coming off a lengthy stint on the sidelines, and has been playing down his chances of going all the way again in Melbourne, where he won in 2009.

Andy Murray hasn't had a match on the center court at Melbourne yet this year, but it hasn't bothered the three-time finalist. He won in straights sets again, beating Joao Sousa 6-1, 6-1, 7-5 to set up a clash with No. 10 Grigor Dimitrov, who labored through a five-set win over 2006 Australian Open finalist Marcos Baghdatis.

Seventh-seeded Tomas Berdych needed eight match points before beating Viktor Troicki 6-4, 6-3, 6-4 and will next play Bernard Tomic, who beat fellow Australian Sam Groth 6-4, 7-6 (8), 6-3.

After having to fend off match points in her previous match, Maria Sharapova made sure it wasn't even close in the third round by beating No. 31 Zarina Diyas 6-1, 6-1 in 61 minutes. She next plays Peng Shuai and has a potential quarterfinal against No. 7 Eugenie Bouchard.

The 20-year-old Canadian struggled through a scrappy opening set before recording a 7-5, 6-0 third-round win over Caroline Garcia that featured 10 breaks of serve.

"I don't think it was the prettiest tennis out there," said Bouchard, who reached the semifinals in her first trip to Melbourne Park last year and went on to make the semifinals or better at two of the other three majors in a breakthrough season.

Third-seeded Simona Halep, who lost the French Open final to Sharapova last year, advanced with a 6-4, 7-5 win over Bethanie Mattek-Sands. Her fourth-round match is against Yanina Wickmayer, who had an upset win over No. 14-seeded Sara Errani.