Youngster Learner Tien and veteran Gael Monfils defied their respective ages as both players reached the Australian Open fourth round.

American qualifier Tien, playing for the first time in the Melbourne main draw, earned a 7-6 (12-10) 6-3 6-3 win over France's Corentin Moutet.

The 19-year-old pulled off the shock of the tournament in the previous round with victory over three-time finalist and fifth seed Daniil Medvedev.

Tien had previously never been beyond the first round at a Grand Slam. He has now become the youngest man since an 18-year-old Rafael Nadal in 2005 to reach the men's singles last 16 at the Australian Open.

Frenchman Monfils, meanwhile, rolled back the years with a fabulous performance to earn a 3-6 7-5 7-6 (7-1) 6-4 win over American fourth seed Taylor Fritz.

The 38-year-old's win over US Open runner-up Fritz means he becomes the second oldest man since 1988 to reach the Australian Open fourth round.

Roger Federer is the oldest in that timeframe, having reached the semi-finals at Melbourne Park in 2020 aged 38 years and five months.

Tien is the first 19-year-old American to reach the fourth round at the Australian Open since 14-time Grand Slam winner Pete Sampras in 1990.

He is one of a trio of teenagers who have impressed with wins over top-10 players in Melbourne.

Brazil's Joao Fonseca, 18, stunned Russian Andrey Rublev in the first round, then 19-year-old Czech Jakub Mensik knocked out Norway's Casper Ruud in the second round.

But while both Fonseca and Mensik have fallen, Tien has advanced to set up a meeting with Italy's Lorenzo Sonego.

"It feels great, obviously," said Tien.

"This has exceeded my expectations, what I was hoping for coming into this week.

"You go into every match believing you can win, but to be in the second week is amazing."

Meanwhile Monfils, a showman and a crowd favourite, continued his rich vein of recent form.

His win over 27-year-old Fritz follows victory at the ASB Classic in Auckland earlier this month, when he became the oldest winner of an ATP Tour singles title.

After serving an ace - his 24th of the match - to see out victory, Monfils danced in celebration before pumping his chest and roaring to the stands.

"I have a strong belief I can still do some damage," Monfils said.

"He started strong but I felt I could move great today."

Monfils' victory came before his wife Elina Svitolina won her third-round tie against Jasmine Paolini on the same court.

"I think I warmed up the court for her," Monfils joked.

"She plays the world number four so it will be tough for her but I hope she will smash this one."

Monfils will play American 21st seed Ben Shelton after he beat Italy's Lorenzo Musetti 6-3 3-6 6-4 7-6 (7-5).