At 19 years of age, Learner Tien becomes the youngest man to reach the Australian Open fourth round since Rafael Nadal.

Teenage qualifier Learner Tien said it was “pretty crazy” after becoming the youngest man to reach the Australian Open fourth round since Rafael Nadal in 2005 when he overcame Frenchman Corentin Moutet on Saturday.

The American 19-year-old won 7-6 (12/10), 6-3, 6-3 in Melbourne with Moutet collapsing clutching his leg in the third set before gamely carrying on.

The victory extended Tien’s remarkable tournament after he stunned last year’s runner-up and fifth seed Daniil Medvedev in a five-set thriller in round two. “Honestly it feels pretty crazy to be in the second week. Going through Qs [qualifying],” he said.

No other American man his age has gone so far in Melbourne since Pete Sampras in 1990, with Tien’s reward a clash against Italian Lorenzo Sonego, who dispatched Hungary’s Fabian Marozsan in four sets.

“This has exceeded my expectations, what I was hoping for coming into this week,” added Tien. “You go into every match believing you can win, but to be in the second week is amazing.”

Tien is one of a trio of teens who set the Australian Open alight with wins over top-10 players, alongside Brazil’s Joao Fonseca and Jakub Mensik, who have both been knocked out since.

In a battle of left-handers, Tien broke early for a 3-1 lead in the first set on the back of an unforced baseline error from Moutet. But the Frenchman levelled at 3-3.

Another exchange of breaks sent it to a dramatic tiebreak that ebbed and flowed before Tien clinched it 12/10, ending a 72-minute set.

The American broke twice in set two to seize control of the match before Moutet collapsed to the ground clutching his left leg after serving at 15-0 in the opening game of the third set.

He got back up and gamely attempted to continue, but was clearly in pain with his movement restricted and Tien took advantage to book a place in a maiden Grand Slam last 16.

“I didn’t really see what was going on… I just saw him on the ground,” Tien said.

“I wasn’t sure what was going on with him honestly because there were some points where it seemed like he wasn’t able to move or really use his legs that much at all.

“Other points he was running and scrapping.”

Sinner takes flight into last 16

Defending champion Jannik Sinner was in a ruthless mood as he powered into the last 16 with a straight-sets thrashing of American Marcos Giron.

The Italian world number one dropped a set for the first time in 14 matches in his second-round clash against Australian wildcard Tristan Schoolkate. There were no such wobbles against the unseeded Giron on Rod Laver Arena as he emphatically sprinted home 6-3, 6-4, 6-2 in 2hrs 1min, slamming 35 winners and eight aces.

Awaiting him next is either Serbian Miomir Kecmanovic or Danish 13th seed Holger Rune, who will face a player on a 17-match win streak. That record stretches back to a defeat against Carlos Alcaraz in Beijing in October.

“Very happy to be in the next round,” said Sinner, who also won the US Open and ATP Finals among eight titles last year. “Every match has its own difficulties. Today I felt like he was very solid from the back of the court, he served well.

“I still have room to improve, but every win is great. Trying to stay there mentally, which I think is the most important aspect for us tennis players,’ he added.

“But for sure, if I want to go on in this tournament I have to improve.”

The 23-year-old, who is defending a Grand Slam title for the first time after his five-set win against Daniil Medvedev in last year’s final, asserted his authority immediately against Giron. He broke him on his first service game and that proved sufficient to take the set, despite making 11 unforced errors, two more than Giron.

The top seed bided his time in set two before making his move in the fifth game, working two break points and taking a 3-2 lead when Giron slapped a forehand wide. The American, who was bidding to reach the last 16 at a Grand Slam for the first time, had no answers as Sinner dominated the rallies.

A Sinner backhand winner earned him another break to move 2-0 clear in the third set and it all looked to be over. But the plucky Giron, ranked 46, still had some fight left and broke for the first time in the match to level up at 2-2.

That riled up the Italian, who broke straight back and made no more mistakes in winning the next four games on his way to victory.