Australia's world number one Ashleigh Barty has been knocked out of Wimbledon, losing her fourth-round match against American Alison Riske.

World number 55 Riske fought back from a set down to win 3-6 6-2 6-3 in one hour 36 minutes on court two to reach a first Grand Slam quarter-final.

French Open champion Barty, 23, had not dropped a set at the tournament.

Riske will face seven-time champion Serena Williams after she beat Spain's Carla Suarez Navarro.

"I couldn't begin to say what it means to me. To have overcome the matches the way I have is what I'm most excited about," said Riske, 29.

"Getting to the quarter-finals is amazing but what's most exciting for me is the way I've been fighting.

"The grass definitely brings out the best in me. Hopefully it will rub off and happen in other places too. I think my game is just well suited to it."

"I love being at Wimbledon. Today I told my fiance, 'I don't want Wimbledon to end'."

Barty is at least guaranteed to hold onto top spot in the rankings after Karolina Pliskova also lost in the fourth round.

The Australian set the early tone as she took the opening game with four successive aces, before a delightful sliced backhand set up break points as the Australian raced into a 4-1 lead.

Unshaken, Riske - who won the pair's only previous meeting in 2016 - brought the set back on serve, only for the world number one to take the final two games and pocket the opener in 32 minutes.

The American rallied in the second set, breaking Barty's faltering serve twice more as the momentum was swiftly stolen away from the Australian.

And, despite losing just 12 games in her opening three matches, Barty was unable to prevent a resurgent Riske continuing her best Wimbledon run as the American made a crucial break at 4-3 in the deciding set.

All four of Riske's matches have gone the distance, with other notable victories coming against 13th seed Belinda Bencic and 22nd seed Donna Vekic during her impressive run.

Barty said: "I think I started well. I was sticking to how I wanted to play. Then in the second set, I think my serve let me down. I let Alison get back into the match too many times, having looks at second serves.

"Overall I didn't play a poor match. When I needed to, when the big moments were there, Alison played better today. It's a tough one to swallow but I lost to a better player."