Stan Wawrinka accepts that his standing in the game has changed after his Wimbledon exit but is still excited about his future.

Wawrinka has won three grand slams and regularly challenged alongside the 'big four' of Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray until he suffered knee problems in 2017.

He has been unable to recapture that level since his return and slipped to a second-round 7-5 3-6 4-6 6-4 8-6 defeat to unseeded American Reilly Opelka having led two sets to one.

At 34, the Swiss accepts he is unlikely to compete at the top end of the men's game again.

"I think before my surgery I was really consistent, finishing top five a few years in a row, playing some big tournaments, going far there," he said.

"Now it's been a bit different. But I'm really happy the way I'm playing.

"Hopefully I can keep playing well. I think I'm playing great tennis.

"Today it's a tough loss, that's for sure. But now it's just a tennis match. The season is really long. There is a lot of tennis to play. I'm excited for the rest of the year."

For Opelka, a 21-year-old who is measured at an inch short of seven foot, it was a first main-round draw win at Wimbledon and just his second ever grand slam win.

Daniil Medvedev, the Russian 11th seed, had no such problems and is through after he beat Australian Alexei Popyrin 6-7 (6) 6-1 6-4 6-4.