San Francisco Frontiers - Teen qualifier Tien stuns Medvedev as Sinner roars back in Melbourne

Taylor Fritz was an emphatic winner in his pursuit of a maiden major title but exciting 18-year-old Joao Fonseca was edged out in a five-set thriller.

The 19-year-old American Tien emerged over a gruelling four hours and 48 minutes of nailbiting action to defeat Russia's Medvedev 6-3, 7-6 (7/4), 6-7 (8/10), 1-6, 7-6 (10/7).

The 121st-ranked Tien next faces France's 69th-ranked Corentin Moutet after the biggest win in his young career.

Tien had defeated Argentina's Camilo Ugo Carabelli in five sets in the first round for his maiden victory at a Grand Slam at the fourth attempt.

"I was definitely hoping it was not going to go to a fifth-set tie breaker," said Tien.

"But just really happy to get a win. I know I made it a lot harder than it could have been, but whatever."

It was a painful exit for former world number one Medvedev, who has lost three of the last four finals at Melbourne Park including to Sinner in 2024.

Before the late-night drama, top-ranked Sinner dropped a set for the first time in 14 matches when he lost the opener to Australian wildcard Tristan Schoolkate.

But he wrested back control after a slow start to go through 4-6, 6-4, 6-1, 6-3 against the world number 173 at a cool and breezy Rod Laver Arena.

It was Sinner's 16th consecutive victory in an ominous sign for next opponent Marcos Giron.

"It's always tough to play against someone I don't know very well. He was playing much better than I was at the beginning," said the Italian, 23, who also won the US Open last year.

"I have to be very happy with my performance and never take things for granted. Very glad to be in the next round.

"I can improve, yes, but I'll take it."

Fritz swept through to a third-round clash against Gael Monfils with a brutal display of power hitting and has dropped just eight games in the tournament so far.

The American fourth seed was untouchable on Margaret Court Arena, swatting aside Chilean qualifier Cristian Garin 6-2, 6-1, 6-0 in 82 minutes.

Fritz only gave up five games to blitz past Jenson Brooksby in the first round and has spent barely three hours on court.

"Always feels great to come out and play a match like that," said Fritz, last year's US Open finalist.

The supremely talented Fonseca has been tipped for the top by Carlos Alcaraz and Novak Djokovic, who has said he sees shades of himself in the Brazilian.

But having stunned ninth seed Andrey Rublev in straight sets in the first round, the teenager went down to Lorenzo Sonego, the Italian pulling through 6-7 (6/8), 6-3, 6-1, 3-6, 6-3 to disappoint the vocal Brazilian fans.

Sonego's reward is a clash against Hungary's Fabian Marozsan, who took down 17th seed Frances Tiafoe, also in five sets.

- Ruthless Swiatek -

In the women's draw, Iga Swiatek set up a showdown with Emma Raducanu in the next round.

Swiatek raced past world number 49 Rebecca Sramkova 6-0, 6-2 while Britain's Raducanu reached the third round for the first time at Melbourne Park by beating Amanda Anisimova 6-3, 7-5.

"Well for sure it's going to be a tough one," world number two Swiatek, a five-time Grand Slam winner but never a Melbourne champion, said as she sized up Raducanu.

"Emma can play great tennis. We all know that."

Raducanu is seeking to claw up the rankings after an injury-hit 2024 and return to the form that brought her a shock US Open crown in 2021 as a qualifier.

"It will be a very good match for me," said the 22-year-old.

Elena Rybakina, the sixth seed and former Wimbledon champion, raced past American wildcard Iva Jovic in straight sets.

Emma Navarro, the eighth seed from the United States, will face Ons Jabeur next after battling through three sets to beat China's 108th-ranked Wang Xiyu.

The Tunisian three-time Grand Slam finalist Jabeur suffered an asthma attack in a 7-5, 6-3 victory over Colombia's Camila Osorio.

"Very, very tough to breathe," she said, adding that she may not have continued if she had lost the first set.

Fourth seed Jasmine Paolini made light work of Renata Zarazua of Mexico, winning 6-2, 6-3 despite some early nerves.

Djokovic, Alcaraz and women's number one and defending champion Aryna Sabalenka all play on a blockbuster Friday.

So do Coco Gauff and Naomi Osaka, who are on a collision course to meet in the next round should they both win.

J.Martinez--SFF