Melbourne - Rafael Nadal said he was "sad" to be out of the Australian Open on Wednesday, depriving him of the chance to equal Roger Federer's 20 Grand Slam titles, but credited "great opponent" Dominic Thiem after their four-set thriller.

The Spanish world No 1 was upset by the Austrian fifth seed in the quarter-finals, losing three tie-breakers as he went down 7-6 (7/3), 7-6 (7/4), 4-6, 7-6 (8/6) it a 4hrs 10mins marathon.

Federer is still in the tournament and plays Novak Djokovic for a place in the final on Thursday as the ageless Swiss hunts for a 21st Slam crown to pull further away from his old rival.

"Of course, I am sad. I lost an opportunity to be in the semi-finals of another Grand Slam," said Nadal. "But I lost against a great opponent. And he deserved it, too. Well done for him."

Defeat also means Nadal, 33, must wait another year to try to become the first man in the Open era - and only the third in history - to win all four Major titles twice, after Roy Emerson and Rod Laver.

The Australian Open is his least successful Slam, having won just once in 2009, and he met his match in fellow baseliner Thiem.

Nadal beat the Austrian in the last two French Open finals and had a 9-4 record in his favour.

But Thiem, 26, rose to the occasion when it mattered with Nadal suggesting his younger legs helped.

"I need a little bit more determination in some moments - true. It's true that in some moments, conditions have been a little bit heavy," he said.

"I had two breaks with new balls. Then I felt more comfortable with the new balls. The ball became so heavy. He's younger, he's very quick. With these heavy balls, it's difficult to produce sometimes winners.

"He has a lot of power, so he's able to produce these amazing shots from a very difficult position."

Asked if there was anything he would have done differently, Nadal replied: "Yes, win any tiebreak."

"But that's how it works. Sometimes things are not going the way that you would like," he added.

"But he played with the right determination. He was putting one more ball in all the time in a difficult position for me. He's playing with a lot of energy, aggressive, determination."