Matteo Berrettini spoke glowingly on the potential of Carlos Alcaraz after battling past the Spaniard at the Australian Open on Friday.

The 2021 Wimbledon finalist managed to make it to the fourth round, despite squandering a two-set lead, as he edged to a 6-2 7-6 (7-3) 4-6 2-6 7-6 (10-5) victory.

Berrettini went down to the 18-year-old, who is the youngest man in the draw of the first grand slam of 2022, in a third-set tie-break loss in Vienna last year.

After securing victory on this occasion in Melbourne, the Italian heaped praise on Alcaraz following their marathon slog that lasted four hours and 10 minutes.

"He is unbelievable," seventh seed Berrettini said of his teenage opponent as he reflected that he did not have a single ATP point to his name at Alcaraz's age.

"He is impressive and will only improve playing matches like this, he has shown everyone his potential. Luckily today I won."

There was a slight concern for Berrettini during the deciding set after the 25-year-old rolled his ankle.

But he was pleased to have fought through his injury problems as he discussed how he almost relinquished his two-set advantage at Rod Laver Arena.

"I felt confident, and that momentum was on my side in the third set but then I got broken," he added during his on-court interview.

"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."

Awaiting Berrettini in the next round will be Alcaraz's fellow Spaniard Pablo Carreno Busta, who defeated Sebastian Korda in four sets to win his third-round tie.