Nadal beat the Italian Mateo Berretini (ATP 7th) with the result 6-3, 6-2, 3-6, 6-3.
Prior to this match, Nadal and Berretini had met once in the semi-finals of the US Open in 2019, in which the Spaniard also won.
Greek Stefan Cicip (ATP 4) and Russian tennis player Danil Medvedev (ATP 2) will compete in the second semi-final.
Nadal is one win away to win his 21st Grand Slam title, ahead of Roger Federer and Novak Djokovic.
The Australian Open will end on Sunday.
