Melbourne - France's Lucas Pouille had never won a match at the Australian Open before this year, but the 28th seed on Monday reached the quarter-finals after beating Borna Coric 6-7 (4/7), 6-4, 7-5, 7-6 (7/2).
The 22-year-old 11th seed from Croatia took a tight first set on a tiebreak that hinged on a couple of points before Pouille responded.
Tenacious 24-year-old Pouille, who endured a Saturday night third round epic against Australian wildcard Alexei Popyrin before coming through in five sets, goes on to meet 16th seed Milos Raonic for a place in the semi-finals.
"It feels great to come through against Borna who is one of the best players in the world, " said Pouille whose best previous Grand Slam performance was reaching the quarter-finals at both Wimbledon and the US Open in 2016.
"It all hinged on a few points here and there," Pouille added of his first victory in three Tour level matches against the former world junior number one who reached a career-high 12th in the world in November.
"Even though I never won a match here before this year I always enjoyed playing here. Atmosphere is great, amazing, electric. That's why they call it the Happy Slam."
Pouille has played Raonic on three previous occasions and is yet to beat the big-serving Canadian.
Their last meeting was at Stuttgart on grass last year
"It was a close match in Stuttgart, " said Pouille of the encounter which he lost 6-4, 7-6 (7/3).
"It's going to be tough one but I'll be ready for it and I'll be trying to reach my first Grand Slam semi-final."