Stefanos Tsitsipas followed up his landmark victory over Roger Federer by beating Roberto Bautista Agut to reach his first grand slam semi-final at the Australian Open.

Backing up breakthrough moments is notoriously difficult but Tsitsipas bucked the trend by battling to a 7-5 4-6 6-4 7-6 (2) win in three hours and 15 minutes.

The 20-year-old Greek had to dig deep on Rod Laver Arena, coming from a break down in the first and third sets before proving stronger in the fourth.

He fell to the court when Bautista Agut's final return landed in the net and can look forward to a clash against either Rafael Nadal or Frances Tiafoe on Thursday.

Tsitsipas' achievement makes him the youngest man to reach the last four at Melbourne Park since Andy Roddick in 2003 and the youngest at any slam since Novak Djokovic at the US Open in 2007.

He said: "It all feels like a fairytale almost. I'm just living the dream, living what I've been working for. I feel a bit emotional but not too much because I know I really worked hard to get here."

The Greek said he had told his team in the off-season that one of his goals for the year was to reach a slam semi-final.

"When I was answering this question I thought I was crazy but it is real and it just happened," he said.

With the match taking place at lunchtime rather than in the evening, the atmosphere was rather more muted than it had been for the Federer clash and the danger of a hangover was immediately apparent.

Federer did not manage to break the Tsitsipas serve at all despite 12 chances but Bautista Agut needed only one game.

However, Tsitsipas responded well, recovering the break to make it 4-4 and then continuing his momentum to win the set.

One break proved enough for Bautista Agut to win the second and it appeared his relentless baseline game may have worn down Tsitsipas when the Spaniard broke for 3-2 in the third.

But Tsitsipas continued to fight and believe, and he got his reward.

As in the first set, he broke back for 4-4 and then made it four games in a row to clinch it, putting behind him a bad forehand miss on his first set point to take it on the third with a backhand slice guided onto the line.

Bautista Agut was finally starting to look weary, which was no surprise given his run through to the last eight.

The 30-year-old needed five sets to beat Andy Murray, John Millman and Marin Cilic, with only a third-round victory over Karen Khachanov being in any way straightforward.

He won a long rally with a forehand onto the line to save a match point at 5-6 in the fourth set, Tsitsipas paying the price for playing a little too conservatively.

The Greek did not make the same mistake in the tie-break, stepping forward and going for his shots, and clinched the win on his second match point.