Melbourne, Jan 21 (IANS): Italian tennis star Matteo Berrettini withstood a spirited fight-back from Spanish teenager Carlos Alcaraz and a nasty fall in the final set to storm into the fourth round of the Australian Open here on Friday.

The world No. 7 squandered a two-set lead and bruised his right ankle in the second game of the fifth set before pulling off an amazing 6-2, 7-6(3), 4-6, 2-6, 7-6(10-5) victory on Rod Laver Arena.

Reflecting on almost letting slip his lead, Berrettini said, "I felt confident, and that momentum was on my side in the third set but then I got broken. My energy wasn't right in the fourth set and in the fifth I just started to think about fighting for every point. In every match something happens (like the ankle injury) but I fought through it."

"I'm very proud of the performance today," Alcaraz was quoted as saying by atptour.com. "It was my first time, two sets down and then to be able to come back the way I did... I gave everything on the court."

Avenging a third-set tie-break loss to the 18-year-old Spaniard in Vienna last year, Berrettini produced a serving master-class early in the match that didn't allow Alcaraz to work his way into the first two sets.

But Alcaraz struck back in third and fourth sets when he put 100 per cent of Berrettini's second serves back into play. Berrettini badly bruised his right ankle in the second game of the fifth set but after receiving treatment, his movement did not appear to be significantly compromised.

Berrettini was full of praise of Alcaraz's game. "At his age I didn't have an ATP point and he will only improve," Berrettini said. "He showed everyone his potential today."

Alexander Zverev of Germany defeated qualifier Radu Albot of Moldova 6-3, 6-4, 6-4 in the third round. The German hit 16 aces and won 83 per cent of points behind his first serve to brush past the world No. 124 in one hour and 57 minutes.

"It's amazing, this is probably my favourite court (in Melbourne), because I've never lost a match here and I hope it continues this way," Zverev said. "The support has been incredible, it's really fun to play in front of all you guys again, and hopefully it will be another good four matches for me."

Zverev's fourth-round match will be a first Grand Slam meeting with 14th seed Denis Shapovalov of Canada, who beat American Reilly Opelka 7-6(4), 4-6, 6-3, 6-4.