MELBOURNE, Australia – Even as his uninterrupted dominance of yore dissipated, even as he took the occasional break, Roger Federer always mattered more often than not in the closing days of Grand Slam tournaments.

Until lately, that is.

Until, at age 37, he was outplayed in the Australian Open's fourth round by a much younger man, 20-year-old Stefanos Tsitsipas, during a 6-7 (11), 7-6 (3), 7-5, 7-6 (5) surprise that ended Federer's bid for a third consecutive championship at Melbourne Park.

"I have massive regrets," said Federer, who was bidding to become the oldest man to reach the quarterfinals in Australia since Ken Rosewall was 43 in 1977.

The match lasted 3 hours, 45 minutes, but Federer essentially cinched his fate two hours in, after he squandered eight break points, including three on unforced errors, to give the 14th-seeded Tsitsipas enough of an opening to squeeze past him in the second set.

Tsitsipas is the first player from Greece to reach a major quarterfinal.

"It was a dream come true for me … just facing him," Tsitsipas said. "Winning at the end? I cannot describe it, you know."

Tsitsipas will take on Roberto Bautista Agut for a place in the semifinals after the Spaniard took down sixth seed and 2018 finalist Marin Cilic 6-7 (6-8), 6-3, 6-2, 4-6, 6-4.

Other results

On the men's side, Rafael Nadal powered into the quarterfinals with a dominant display, beating Tomas Berdych 6-0, 6-1, 7-6 (7-4). Nadal will face American Frances Tiafoe, who celebrated his 21st birthday by stunning 20th seed Grigor Dimitrov 7-5, 7-6 (8-6), 6-7 (1-7), 7-5.

Sixteenth-seeded Milos Raonic upset No. 4-seed Alexander Zverev 6-1, 6-1, 7-6 (5) to reach the Aussie quarterfinals for the fourth time.

On the women's side, three of the quarterfinals were set heading into the overnight session, which included a fourth-round match between No. 1 Simona Halep and No. 16 Serena Williams. Russian Anastasia Pavlyuchenkova will play American Danielle Collins after ousting fifth seed Sloane Stephens 6-7 (3-7), 6-3, 6-3. Eighth seed Petra Kvitova will play No. 15 Ash Barty, and No. 4 Naomi Osaka will play No. 6 Elina Svitolina.

Svitolina fended off five break points in third-set game that went to deuce 11 times, contained 28 points, and was pivotal in a momentum-swinging 6-2, 1-6, 6-1 win over 17th-seeded American Madison Keys.