Monfils was struggling with a back injury at the start of the fourth set as Ben Shelton advanced to the quarter-finals

Jannik Sinner battled through illness and reached the quarter-finals of the Australian Open on Monday but the physical demands of Grand Slam tennis proved too much for French veteran Gael Monfils and American teenager Learner Tien.

Veteran Gael Monfils has rolled back the years in recent weeks with a string of incredible performances, but the Frenchman said he had exceeded his limit after retiring hurt from his fourth-round Australian Open match against Ben Shelton on Monday.

Learner Tien, 19, beats Corentin Moutet while Gael Monfils, 38, defeats fourth seed Taylor Fritz to reach the Australian Open fourth round.

After his historic win, Monfils returned to Margaret Court Arena and sat in the stands to watch his wife, Svitolina, eliminate the women's No. 4 seed, two-time major finalist Jasmine Paolini 2-6, 6-4, 6-0 at night.

The 19th-seeded Shelton looks to match his best major showing, a semifinal at the 2023 US Open. Earlier that year, Shelton advanced to the last eight Down Under on his first international trip. Fellow unseeded American, Tommy Paul, ultimately ended that run.

Elina Svitolina revealed she had been inspired by her husband Gael Monfils after the couple both completed thrilling upsets in their respective matches at the Australian Open. Svitolina staged a brilliant comeback to beat fourth seed Jasmine Paolini 2-6 6-4 6-0 in their third-round meeting.

It was a day to remember at the Australian Open, with Learner Tien becoming the youngest to reach the fourth round since Rafael Nadal in 2005 and Gael Monfils defying age to tie French records and make history.

Defending champion Jannik Sinner raced to victory at the Australian Open on Saturday to sweep into the last 16 as Iga Swiatek demolished Emma Raducanu.

French veteran Gael Monfils battled through a five-set thriller to topple young countryman Giovanni Mpetshi Perricard at the Australian Open on Tuesday as he enjoys a late-career resurgence. Monfils won the first two sets and should have wrapped it up in the third,

Veteran Lorenzo Sonego reached his first Grand Slam quarterfinal after beating 19-year-old qualifier Learner Tien 6-3, 6-2, 3-6, 6-2. The 29-year-old was unstoppable on serve and handled the stifling conditions better than Tien, whose breakout tournament was highlighted by an upset of fifth seed Daniil Medvedev in round two.