Il Nuovo Postiglione - Veteran Monfils stuns fourth seed Fritz at Australian Open

The 38-year-old Frenchman fought back 3-6, 7-5, 7-6 (7/1), 6-4 to make the fourth round for a sixth time in his 19th Australian Open.

He is the second-oldest man to reach the last 16 at Melbourne Park after Roger Federer.

Fritz had been in sizzling form before he met Monfils, dropping just eight games in his two previous matches.

But the unseeded Frenchman was a different beast, unrelenting with his precision groundstrokes and booming serve to wear down the world number four.

Monfils, ranked 41, fired a warning ahead of the tournament when he won the Auckland Classic to become the oldest singles champion in ATP Tour history.

"The strategy was to hold the baseline and definitely change the tempo. Hit some big shots down the line and used some shape with my forehand, some slice with my backhand and served well," he said.

"I have a strong belief in myself, a strong belief I can still do some damage and with a little bit of luck we are in the second week of the Australian Open."

He will meet another American, Ben Shelton, or Italy's Lorenzo Musetti for a quarter-final berth.

Monfils has never been beyond the semi-finals of a major in his long career.

The pair went toe-to-toe at the start with some big baseline rallies, one stretching to 29 shots and another to 24.

A Monfils double fault handed Fritz a break for 5-3, with the American holding serve to secure the first set.

The baseline battle continued in the next set with neither player able to work a break-point opening until Fritz was serving to level up at 5-5.

He lost his focus and the wily Monfils -- who won a remarkable 95 percent of first-serve points -- enticed a series of errors and broke to love for the set.

Fritz needed a medical timeout at the changeover for treatment on his right foot, then saved two break points to stay on serve at 3-3.

The third set went to a tiebreak, where the Frenchman destroyed an increasingly frustrated Fritz, racing 6-0 clear with a series of sizzling shots and winning the set.

Monfils dug deep to win an 18-point fourth game in the fourth set, saving two break points, then pounced on the Fritz serve to break for a 5-4 lead before completing the upset.

E.Accardi--INP