Berrettini (middle) needed treatment on his ankle early in the final setDates:17-30 January Venue: Melbourne ParkCoverage: Daily radio commentaries on BBC Radio 5 Live Sports Extra, BBC Sport website and app, with selected live text commentaries online; TV highlights from middle Saturday.Seventh seed Matteo Berrettini overcame Spanish prospect Carlos Alcaraz in an enthralling five-set battle to reach the Australian Open fourth round.
Italian Berrettini established a two-set lead before 18-year-old Alcaraz, the youngest man in the draw, fought back to take it to a thrilling fifth.
Berrettini held his nerve to win the deciding tie-break 6-2 7-6 (7-3) 4-6 2-6 7-6 (10-5) at the Rod Laver Arena.
"He is unbelievable," said 25-year-old Berrettini of his teenage opponent.
"He is impressive and will only improve playing matches like this, he has shown everyone his potential. Luckily today I won."
The Wimbledon finalist looked in control for the first set and most of the second before Alcaraz grew in confidence, breaking back and taking it to a tie-break that he lost.
But the signs were there and the young Spaniard clinched the third set before storming through the fourth to set up a decisive finale.
Berrettini turned his ankle early in the set and needed treatment, but the Italian dug in to fend off a break point and then brought up match point at 6-5.
Alcaraz, who beat Berrettini at the Erste Bank Open in Austria last year, saved the point with a fizzing second serve and battled back to hold and force the tie-break.
However, it was the more experienced Berrettini who edged ahead and did not let up in the first-to-10 decider, winning a match that lasted more than four hours.
German third seed Alexander Zverev had a more straightforward passage into the last 16, seeing off Moldovan qualifier Radu Albot 6-3 6-4 6-4.
Zverev will now play Canadian 14th seed Denis Shapovalov, who beat American Reilly Opelka 7-6 (7-4) 4-6 6-3 6-4.
French 17th seed Gael Monfils overcame Chile's 16th seed Cristian Garin 7-6 (7-4) 6-1 6-3 and will play Serb Miomir Kecmanovic, who knocked out Italian 25th seed Lorenzo Sonego 6-4 6-7 (8-10) 6-2 7-5.
