LONDON - Defending champion Carlos Alcaraz and world number one Jannik Sinner stayed on track for a blockbuster Wimbledon showdown by reaching the quarterfinals, while women's second seed Coco Gauff was sent tumbling out on a soggy Sunday.

French Open champion Alcaraz, who is looking to defend his Wimbledon trophy and complete what is dubbed the "Channel Slam" in reference to the English Channel that separates Britain and France, battled past Metz-born Ugo Humbert 6-3 6-4 1-6 7-5.

"I think I'm getting better and better every match that I'm playing," said Alcaraz, who was happy to avoid another five-set tussle after being taken the distance by Frances Tiafoe in the previous round.

Italian Jannik Sinner, who could face Alcaraz in the semi-finals in a rematch of their Roland Garros meeting, was equally impressive in his 6-2 6-4 7-6(9) win over 14th seed Ben Shelton

"I'm feeling really comfortable on the court and hitting good points, good shots."

American 12th seed Tommy Paul set up a last-eight meeting with the 21-year-old Spaniard after the Queen's Club champion downed Roberto Bautista Agut 6-2 7-6(3) 6-2.

Italian Sinner, who could face Alcaraz in the semifinals in a rematch of their Roland Garros meeting, was equally impressive in his 6-2 6-4 7-6(9) win over 14th seed Ben Shelton.

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"I'm happy how I handled the situation," said Sinner, who neutralised the feisty American's big serves to prevail.

"It was obviously very, very tough to play against him, one of the best servers we have on tour, very aggressive player.

"I'm happy how I returned today. Yeah, I think that's for sure one of the keys today."

The 22-year-old will next meet fifth seed Daniil Medvedev, who he defeated in January to win his maiden Grand Slam title at the Australian Open.

Russian Medvedev progressed when Bulgarian 10th seed Grigor Dimitrov retired from their clash while trailing 5-3.

There was heartbreak for British fans as their last hope Emma Raducanu was dumped out by 123rd-ranked qualifier Lulu Sun who sealed a 6-2 5-7 6-2 win over the 2021 US Open winner

Sinner's fellow Italian Jasmine Paolini also advanced thanks to an injury to her opponent, as the teary Madison Keys withdrew at 5-5 in the deciding set of their encounter with a suspected groin problem.

"I hope she recovers soon. We played a really good match. Of course, it's not the easiest to end like this," Paolini said.

"But I have to say that a part of me is happy to be here in the quarter-final in Wimbledon."

There was heartbreak for British fans as their last hope Emma Raducanu was dumped out by 123rd-ranked qualifier Lulu Sun who sealed a 6-2 5-7 6-2 win over the 2021 US Open winner.

Reigning Flushing Meadows champion Coco Gauff did not fare any better as she was hammered 6-4 6-3 by fellow American and 19th seed Emma Navarro.

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Donna Vekic overcame several rain delays to get past Spain's Paula Badosa 6-2 1-6 6-4 and book a clash with Sun.