Melbourne - Former champion Stan Wawrinka said he played his best match since knee surgery threatened to derail his career as he upset world number four Daniil Medvedev on Monday to race into the Australian Open quarter-finals.
The popular Swiss star, who beat Rafael Nadal in the 2014 decider, dug deep to come from behind in five intense sets and win 6-2, 2-6, 4-6, 7-6 (7/2), 6-2.
It set up a last-eight clash with either Russian 17th seed Andrey Rublev or German seventh seed Alexander Zverev.
"I think last time I played so well was before the surgery. I think for sure, I feel since the off-season my level is really high. Physically I'm moving better than last year. So I'm improving," he said.
Three-time Grand Slam champion Wawrinka has not won a title since pocketing the 16th of his career on the Geneva clay in 2017, with two bouts of surgery on his left knee that year pushing him to the brink of retirement.
A lengthy absence from the tour meant his world ranking plunged, but he has climbed back to world number 15 after runs last year to the last eight at Roland Garros and the US Open.
He said tennis was still his passion, with no signs of retirement despite being 34.
"I'm playing, traveling around the world, playing in front of people, getting a lot of emotion from it. I love the process, also the way you have to try to improve, the time you need to put in the practice court to get to your level," he said.
"I don't know how many years left. I want to do the maximum with it."
Beating Medvedev brought up another milestone in Wawrinka's illustrious career - it was his 300th Tour-level win.
"The level was super-high and atmosphere is so special here in Australia," said Wawrinka, who is into his 18th Grand Slam quarter-final, behind only Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray among active players.
"It's amazing to still be playing and at that level. I'm really happy with what I'm doing on the court."
It was classic Wawrinka in the first set, as he broke to go 3-1 in front and then again to take the set in 32 minutes of precision and power, with the Russian struggling to match him around the court.
But Medvedev came roaring back to break and take a 3-1 lead in the second set as Wawrinka lost his range, breaking again to take the set in emphatic fashion.
The 23-year-old built on his advantage early in the third set, with his serve making life hard for Wawrinka who struggled to create chances and had trouble applying the finishing touch at the net.
In contrast, Medvedev was hitting winners and broke for 4-3 before sealing the set.
They traded blows in a tight fourth set, with Wawrinka showing his experience to win the tie-breaker and send it to a deciding set, where the writing was on the wall.
Medvedev had played five career five-setters and lost them all, while veteran Wawrinka had 50 under his belt and a 28-22 record.
He turned the screws, breaking the Russian's opening service game then staving off three break points to go 3-1 in front, with no way back for the fourth seed.
Results on day eight of the Australian Open Grand Slam at Melbourne Park on Monday (x denotes seeding):
Dominic Thiem (AUT x5) bt Gael Monfils (FRA x10) 6-2, 6-4, 6-4
Stanislas Wawrinka (SUI x15) bt Daniil Medvedev (RUS x4) 6-2, 2-6, 4-6, 7-6 (7/2), 6-2
Anett Kontaveit (EST x28) bt Iga Swiatek (POL) 6-7 (4/7), 7-5, 7-5
Simona Halep (ROU x4) bt Elise Mertens (BEL x16) 6-4, 6-4
Garbine Muguruza (ESP) bt Kiki Bertens (NED x9) 6-3, 6-3