Switzerland's Roger Federer waves during a 100 years of Centre Court celebration on day seven of the Wimbledon tennis championships in London, July 3, 2022. (KIRSTY WIGGLESWORTH / AP)

LONDON - Swiss tennis great Roger Federer joined more than 20 Wimbledon champions to celebrate the 100-year anniversary of the Center Court at the All England Club in London on Sunday.

The eight-time Wimbledon champion walked into the Center Court last and received standing ovation from a wild crowd.

I've been lucky enough to play a lot of matches on this court. It feels awkward to be here today in a different type of role. I hope I can come back one more time. I've missed it here. I knew walking out here last year, it was going to be a tough year ahead.

Roger Federer, tennis player

"I've been lucky enough to play a lot of matches on this court. It feels awkward to be here today in a different type of role," said Federer, who missed this year's tournament as he is still trying to recover from a knee surgery.

"I hope I can come back one more time. I've missed it here. I knew walking out here last year, it was going to be a tough year ahead. I maybe didn't think it was going to take this long to come back - the knee has been rough on me," said the 40-year-old who was knocked out of the quarterfinals at last year's Wimbledon Championships.

Federer's long-time rivals Rafael Nadal and Novak Djokovic both attended the celebration while the 35-year-old Serbian walked into the Center Court again later in the evening to play his round of 16 match against Dutchman Time van Rijthoven.

Djokovic keeps his hope of winning the Wimbledon trophy for a seventh time alive after beating the 25-year-old Grand Slam debutant 6-2, 4-6, 6-1, 6-2.

Djokovic will fight for a semifinal berth against Italian 10th seed Jannik Sinner as the 20-year-old defeated fifth seed Carlos Alcaraz from Spain 6-1, 6-4, 6-7, 6-3.

Alcaraz has proven his potential on clay as the 19-year-old's four out of five titles so far were from the surface. But winning three matches in a row at this year's grass-court Grand Slam has given the teenager more confidence on grass.

"I felt really well here. I got a lot of experience playing on grass. Now I'm thinking that myself could be a great player on grass," he said.

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In the women's singles, third seed Ons Jabeur from Tunisia reached the quarterfinal for a consecutive second year after beating Belgian Elise Mertens 7-6 (11-9) and 6-4.

Mom-of-two Tatjana Maria from Germany ousted 12th seed Jelena Ostapenko of Latvia 5-7, 7-5 and 7-5.