Sinner battles through but seeds tumble in day of shocks in Rotterdam

The 22-year-old Italian, unbeaten this year, showed the imperious form that took him to victory in Melbourne from the start, racing into a 3-0 first-set lead.

Wildcard Monfils, 37, entertained the crowd with some trademark retrieving and the occasional trick shot but initially had no answer to Sinner's consistency, losing the first set 6-3.

But the Frenchman, now 70th in the world, rolled back the years in the second set, delighting the Rotterdam crowd that saw him win back-to-back titles in 2019 and 2020.

Cleverly mixing blistering forehands and well-judged drop shots, he disturbed Sinner's rhythm and broke serve early in the second set, hanging on to close it out 6-3.

A poor Monfils first service game in the deciding set, riddled with unforced errors and a double-fault, handed the initiative back to the Italian, who again opened up a 3-0 advantage.

Sinner's relentless pressure told and the world number four eventually broke the French resistance, finishing off the third set 6-3.

"It's always tough to play against him. He won two times here, so he knows how to play here," said Sinner.

"I'm very happy. I was struggling a bit, I didn't have so much rhythm."

"But in these kind of matches you learn a lot. It gives me confidence for the next one," against Canada's Milos Raonic.

'Biggest win'

Earlier in the day, rising star Holger Rune suffered a shock defeat to Kazakh Alexander Shevchenko and local hero Tallon Griekspoor beat fourth-seed Hubert Hurkacz in a thriller with the help of raucous crowd support.

Both winners said the victories were their "biggest" or "best".

Shevchenko, the 23-year-old world number 57, won 6-4, 1-6, 6-3 for only his second career victory against a top-10 player to set up a quarter-final clash against Bulgaria's Grigor Dimitrov.

In a topsy-turvy match, Shevchenko won a tight first set 6-4 before capitulating 6-1 in the second. The deciding set went on serve until 4-3 before the Kazakh broke in the eighth game.

"It's the biggest win of my career. I'm really proud of myself," said Shevchenko.

"Already last year, I played some good tennis but I needed the experience of playing top guys like Hurkacz, Rune, (Daniil) Medvedev, Sinner. Now I got it and I'm trying to find a way day by day to play them."

He predicted a very different challenge against Dimitrov, who tends to employ more slice while Dane Rune relies on a hard serve and powerful forehand.

"I don't really know how you can prepare for Grigor. He's playing some insane tennis at the moment," said Shevchenko.

Griekspoor, the world number 29, showed his battling qualities, coming through 7-6 (7/5), 6-7 (5/7), 7-6 (7/4).

"I'm unbelievably happy. It's the best win of my life," he said.

"This is the reason I play tennis, to play these kinds of matches... I'm really proud of what I did. It shows what I can do," added the 27-year-old Dutchman.