Qualifier Learner Tien stuns Daniil Medvedev in late night epic

Inspired American teenager Learner Tien outlasted three-times Australian Open runner-up Daniil Medvedev to reach the third round with a 6-3, 7-6(4), 6-7(8), 1-6, 7-6(7) victory in a late-night epic on Thursday.

Qualifier Tien's hopes seemed to be fading after fifth seed Medvedev saved a match point with an ace in the third set tiebreak as the Russian stormed back from two sets down to set up a decider in Margaret Court Arena.

However, the 19-year-old lefthander tapped into his last reserves of energy and came up with some dazzling tennis to deliver the biggest shock so far in Melbourne and become the youngest American man to reach the third round at the Australian Open since Pete Sampras did so aged 18 in 1990.

"I mean, I was definitely hoping it wasn't going to go to a fifth set breaker, Tien, who was born in California to Vietnamese parents, told the crowd who stayed for the climax of the four hour 49 minute contest that ended at nearly 3 a.m.. "Either way, I was just really happy to get a win. I know I made it a lot harder than maybe it could have been. But you know, whatever."

Tien had lost in the opening round in his first three Grand Slam appearances but marked his Australian Open debut by beating Camilo Ugo Carabelli in five sets to line up a clash with Medvedev.

He reeled off five successive games to take the opening set from 3-1 down and showed incredible tactical awareness and clinical precision as he kept a rather passive Medvedev at full stretch during a second set littered with service breaks.

Tien failed to close out the set when serving at 6-5 but snatched the tiebreak with an ice-cool forehand winner.

It looked like a pivotal moment as Medvedev took the third set and sped through the fourth with Tien finally appearing to be suffering physically.

Medvedev looked to be the clear favorite in the decider but world number 121 Tien courageously matched with the Russian in a series of grueling rallies that grew ever more intense.

After a brief rain delay at 5-5, former U.S. Open champion Medvedev served for the match at 6-5 but Tien refused to go away and broke back to send the contest into a first-to-10 breaker.

Again it looked as though Medvedev would survive to fight another day as he moved 6-4 ahead but the fearless Tien won six of the last seven points, clinching a memorable victory on his first match point as a weary Medvedev floated a return long.

In the women's event, last year's French Open and Wimbledon finalist Jasmine Paolini brushed aside Mexico's Renata Zarazua 6-2, 6-3 to reach the third round, where the fourth-seeded Italian will face Ukrainian 28th seed Elina Svitolina.

Elena Rybakina sent another teenager packing from the Australian Open after the sixth seed overcame a second-set wobble to beat American wildcard Iva Jovic 6-0, 6-3.