Only once in Nadal's grand slam career had he previously let a two-set lead slip and such a slump appeared entirely improbable as he dominated Tsitsipas on Rod Laver Arena.

But the 20-time major champion, chasing a record-breaking 21st title, struggled to recover his momentum after dropping a set for the first time in the tournament when the third went to a tie-break.

The courageous Tsitsipas grew in confidence and landed a momentous second career win over Nadal to reach a third slam semi after a four-hour 3-6 2-6 7-6 (7-4) 6-4 7-5 epic.