|Australian Open 2019|
|Venue: Melbourne Park Dates: 14-27 January|
|Coverage: Daily live commentaries on the BBC Sport website, listen to Tennis Breakfast daily from 07:00 GMT on BBC Radio 5 live sports extra and watch highlights on BBC TV and online.|
Defending champion Roger Federer is out of the Australian Open after Greek 14th seed Stefanos Tsitsipas earned the biggest win of his career to reach the quarter-finals.
The Swiss lost 6-7 (11-13) 7-6 (7-3) 7-5 7-6 (7-5) on a dramatic night.
Federer, a six-time champion, failed to reach the last eight in Melbourne for only the second time in 16 years.
Tsitsipas, 20, saved all 12 of 37-year-old Federer's break points on his way to a famous win.
"I'm the happiest man on earth right now, I can't describe it," he said.
"I beat my idol. My idol today became pretty much my rival."
Federer lumped a forehand long to leave Tsitsipas serving for the match in the fourth-set tie-break, and the youngster forced him into a backhand error to win in three hours and 45 minutes.
Tsitsipas dropped his racquet in celebration and seemed to mouth "me?" at the crowd, expressing his shock further by covering his hand with mouth, before starting to cry as he walked over to celebrate with his team.
"That moment is definitely something that I will never, ever, ever forget," he said.
"This match point is going to stay, I'm pretty much sure, forever, for the rest of my life."
He will play Spain's Roberto Bautista Agut, who beat Croatian sixth seed Marin Cilic in five sets, in the last eight.
And the Greek believes he is on the verge of "something big" and could perhaps even win the tournament.
"That's why I'm here, playing to win the trophy," he said. "I want it really badly."
- Federer targets clay season return after Australian Open exit
- Federer v Tsitsipas as it happened
- Profile: Who is Stefanos Tsitsipas?
Federer rues missed opportunities
Federer was aiming to win a record seventh men's singles title at Melbourne Park, moving him clear of world number one Novak Djokovic and Australian legend Roy Emerson.
But the 20-time Grand Slam champion was undone by a player considered to be one of the best hopes to take over the mantle when Federer - along with Djokovic and Rafael Nadal - retires.
The pair were contesting their first ATP-level match, although did meet last month in a Hopman Cup tie which Federer edged in two tie-breaks, indicating their contest in Melbourne could be equally tight.
Tsitsipas' fearless and energetic approach unsettled Federer, seemingly putting doubt in the former world number one's mind on the key points.
Federer failed to convert any of 12 break points, with some errant forehands particularly letting him down.
"There are always multiple factors in match like this, but it didn't go well on the set points," he said.
"I didn't break him at the Hopman Cup either, so something is going wrong. It is very frustrating."
The most significant were the eight which he could not take in a six-game spell in the second set - specifically the four which were set points in a nerve-wracking 10th game.
For three consecutive service games, Tsitsipas was put under severe examination in lengthy battles which the Greek eventually came through unscathed.
That enabled him to go on and level in the tie-break - a pivotal moment which turned the match in his favour.
"I could have cracked at any moment, but I didn't because I really wanted it bad," said Tsitsipas.
"That mental toughness helped a lot. It could have been a different match if I didn't stand that pressure."
Federer had lost his past two Grand Slam matches after dropping sets for the first time in the tournament - against Kevin Anderson at Wimbledon and John Millman at the US Open - and he suffered the same fate again.
"I lost to a better player who played very well. He stayed calm and hung in there, which is not easy for younger guys so credit to him," Federer added.
Breakthrough victory for rising star
Tsitsipas has enjoyed a rapid rise over the past 18 months, becoming the first Greek man to reach the world's top 100 in October 2017 and then climbing to his current ranking of 15th.
That transferred into trophies when he won his first ATP Tour title at the Stockholm Open last October, going on to win the NextGen Finals - the end-of-season finals for the best players aged under 21 - in December.
Yet this is the landmark win at a Grand Slam which will now announce his arrival to a wider audience.
It was not all about digging in on the break points, however.
Tsitsipas matched Federer in a high-quality encounter, producing 61 winners - bettering the Swiss' tally by one - and succeeding in 71% of his 68 forays forward to the net.
He limited his unforced errors to 38, compared to 55 from Federer which included 40 from his forehand alone.
Although most fans inside Rod Laver Arena were pro-Federer, everybody watching cannot have failed to have been impressed by Tsitsipas' all-action style.
"I believe in coming into the net and being aggressive and taking the ball early, we have to keep it going," he said.
"Most players in this era are baseliners. I like this aggressive game, coming into the net, and serve and volleying now and again.
"It keeps the game alive and makes it much more interesting."
Fading stamina fact of life for Federer - analysis
BBC tennis correspondent Russell Fuller at Melbourne Park
Stefanos Tsitsipas offered Roger Federer no respite. His level never dipped, and he set the platform for a famous victory by fending off four break points and four set points to win the second set.
The first signs of alarm for the Swiss came in the third set. He may have won this title for the past two years, and an eighth Wimbledon title in the months in between, but fading stamina is a fact of life even for Federer when he is playing a five set match against a man 17 years his junior.
Last year, Federer did not drop a set en route to the final, but he lost in five to Kevin Anderson at Wimbledon and in four to John Millman on a brutally humid night at the US Open.
Federer announced afterwards that he plans to play at this year's French Open for the first time since 2015. That will be cause for great rejoicing in Paris, but you do have to wonder what impact that will have on his chances at Wimbledon.