The 20-time Grand Slam champion – level with Roger Federer and Novak Djokovic for the most men’s Grand Slam singles titles in history – will face Berrettini in the semi-finals at Melbourne Park on Thursday.
He is chasing a second title Down Under after winning the Australian Open back in 2009 – and Nadal sent a warning to Berrettini, who defeated Gael Monfils on Tuesday.
“Matteo, he’s one of the best players of the world since a while already. He’s very solid,” said Nadal.
“I need to play my 100 per cent and my highest level if I want to keep having chances to fight, to be competitive, and to try to be in the final.
“I am super happy today. For me, this victory is super important in these circumstances, and be able to win [and reach] the semi-finals of a Grand Slam after everything is a lot of positive energy for me.”