Russian qualifier Aslan Karatsev came from two sets down to pull off yet another stunning victory to reach the Australian Open quarter-finals.
The 27-year-old world number 114 beat Canadian 20th seed Felix Auger-Aliassime 3-6 1-6 6-3 6-3 6-4.
With victory over eighth seed Diego Schwartzman in the previous round, Karatsev has been the surprise package at this year’s event at Melbourne Park.
He is the first man to reach a major quarter-final on debut for 25 years.
Dogged by injury during his career, Karatsev had failed in nine previous attempts to reach a Grand Slam main draw, but at the ATP Cup earlier this month he was described by world number four Daniil Medvedev as Russia’s “secret weapon”.
He has more than proved this, having reached the fourth round without dropping a set before mounting an incredible comeback against Auger-Aliassime in the first five-setter of his career to set up a last-eight meeting with US Open champion Dominic Thiem or Bulgarian former world number three Grigor Dimitrov.
“I’ll be ready for everyone,” said Karatsev, who is the first man since Alex Radulescu in 1996 to make it to the last eight on their Grand Slam debut.
Thiem faces Dimitrov on Sunday before world number one Novak Djokovic is due to take on Canada’s Milos Raonic. The Serbian top seed has expressed doubt over his fitness after picking up an abdominal injury in the previous round.