Australia's Alexei Popyrin fought back from a set down and overcame cramping to shatter Stan Wawrinka's hopes of a first title in six years by winning the Umag clay-court title on Sunday.

The 23-year-old Popyrin, ranked at 90 in the world, came through 6-7 (5/7), 6-3, 6-4 after two hours and 36 minutes on court to claim a second career title to add to his 2021 Singapore victory.

Three-time major winner Wawrinka, 38, was hoping to capture a 17th career title but first since Geneva in 2017. 

Wawrinka recovered from 3-5 down in the opening set before claiming the tie-breaker.

Popyrin, 15 years Warinka's junior, levelled by pocketing the second set and was a break ahead in the first game of the decider which he immediately handed back.

The young Australian suffered cramping in the heavy, humid conditions and called for the physio but still carved out the key break in the ninth game before serving out for victory.

"All tournament I've been fighting battles that I don't know how I won. This one tops it all," Popyrin said on court.

"I felt cramp, I felt (the muscle) strain but I managed to dig deep. I don't know how I won it.

"The physio said, 'If you go any more then it will be tough'. I said, 'There's no point in quitting now, I'm here in the final. If I lose, I lose. If I retire, I lose anyway. So I have a better chance of winning if I stay in', so that's what I decided to do."

Despite defeat, former world number three Wawrinka will return to the top 50 next week having fallen out of the top 300 after undergoing two surgeries on his feet in 2021.

Popyrin, in turn, will reach a career-high 57.

"It's an unbelievable honour to play somebody like Stan in a final," added the Australian.

"I grew up watching him, Roger, Rafa, Novak play. To play him in a final and beat him in a final, words can't describe how happy I am. It’s an unbelievable feeling."

dj