Ash Barty's Wimbledon charge has come to a shuddering halt at the hands of free-swinging American Alison Riske.

Key points: Ash Barty's 15-match winning streak is at an end, as well as her hopes of a French Open-Wimbledon double

Ash Barty's 15-match winning streak is at an end, as well as her hopes of a French Open-Wimbledon double Barty started like a house on fire with four aces in the opening game, but Riske fought back to win in 97 minutes

Barty started like a house on fire with four aces in the opening game, but Riske fought back to win in 97 minutes World number 55 Riske will face Serena Williams in an all-American quarter-final

Bidding to become the first Australian woman to make the quarter-finals at the All England Club since Jelena Dokic 19 years ago, Barty fell 3-6, 6-2, 6-3 in a fourth-round nail-biter on Monday.

Unseeded Riske withstood 12 aces from Barty to chalk up her tour-best 14th grass court victory of the season.

The Court 2 boilover also ended Barty's 15-match winning streak and scuppered the 23-year-old's hopes of completing a rare French Open-Wimbledon title double.

Barty even delved deeper into her back-catalogue of Disney quotes to reference musical Annie in her post-match media conference as she kept the defeat in perspective.

"It's disappointing right now, but you give me an hour or so and I'll be all good," Barty said.

"The Sun's still going to come up tomorrow.

"I didn't win a tennis match. It's not the end of the world," Barty continued.

"Overall it's been a hell of a trip, [though I'm] disappointed right now. Obviously it's a tough pill to swallow, in the same breath it's been an incredible few months."

In reference to her Disney quotes, Barty admitted she loves Disney and the references were her way of adding a bit of fun to the proceedings.

"Well, it's [had] a bit of interest, hasn't it?" Barty said.

"Look, it was a way for us to enjoy it and try to bring a little bit more energy, I suppose, in the press. I love Disney. I watch it all the time.

"Look, it's been a bit of fun for all of us. You guys caught on I think the third time around. It's been a bit of fun."

An upset looked remote when Barty fired down four aces to start the match before taking the opening set in 32 minutes.

Riske was unfazed, calmly working her way into the contest with some fearless hitting from the baseline.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 42 seconds 42 s Top seed Ash Barty crashed out of Wimbledon in a loss to American Alison Riske

Piling the pressure on Barty with sustained attack and measured forays to the net, Riske broke Barty twice to seize the second set to make a fool of her ranking of number 55 in the world.

Staving off a break point in the fourth game of the deciding set, Riske nabbed another crucial break with a massive forehand winner to surge ahead 5-3, before retaining her poise to clinch a shock victory after one hour and 37 minutes.

"I couldn't begin to say what it means to me," Riske said.

"I think ultimately just to have overcome the matches the way that I have, I think that ultimately is what I'm most excited about.

"Obviously getting to the quarter-finals is amazing, I think just the way I've been fighting, for me that's what is most exciting for me. But I must say being at Wimbledon is not too bad."

Riske will face compatriot Serena Williams in an all-American clash for a place in the semi-finals at the All England Club, after Williams beat Spain's Carla Suarez Navarro 6-2, 6-2.

Serena Williams has progressed to the quarter-finals despite a lack of match practice heading in to Wimbledon. ( AP: Kirsty Wigglesworth )

Williams, 37, aiming for a record-equalling 24th Grand Slam title, produced 19 unforced errors, including a bizarre mistake when she leaned over the net to hit a volley and had the point docked.

But she also conjured 21 winners, some of which left the crowd gasping in admiration and her 30-year-old opponent helpless on the other side of the net.

Williams, seeded 11th, had little match practice coming into Wimbledon because of injury and teamed up with Andy Murray in the mixed doubles to get some more playing time.

"I've had more matches this week than the past five months but it's definitely good and I know I can play and I'm now physically better [so] it's almost a feeling of relief more than anything," she said immediately after coming off court.

Fairytale over for Coco

The story of the tournament in 15-year-old American sensation Cori 'Coco' Gauff has come to an end after a straight-sets loss to seventh seed Simona Halep.

Coco Gauff couldn't keep the fairytale alive at the All England Club in a straight-sets loss to Simona Halep. ( AP: Kirsty Wigglesworth )

The Romanian — the seventh seed and former world number one — proved far too good for the Wimbledon debutant, winning 6-3, 6-3 in only 75 minutes.

After stunning Venus Williams then saving two match points en route to beating Polona Hercog last week, Gauff was suddenly the hottest ticket in town but she was always going to find it tough against Halep, last year's French Open champion and the first top-10 opponent she had ever faced.

Bidding to become the youngest Wimbledon quarter-finalist since fellow-15-year-old Jennifer Capriati in 1991, Gauff was by no means overawed, keeping the crowd entertained with some crashing backhands and athletic recoveries, but there were also far too many simple errors that the American was never going to get away with at this stage of the tournament.

Halep, who had given an indication of her form when dismissing the dangerous Victoria Azarenka in the last round, initially struggled, including in the third game where she sent down three successive double faults.

But Gauff was even more inconsistent, mixing up some superb shots with some pretty awful ones.

Halep then began to find her range and quickly realised that she did not need to take too many risks, keeping the ball in play, accepting that the occasional winner would whistle past her but more often winning the point via a Gauff mistake.

That was enough to take the first set and the pattern continued, with more emphasis in a quickfire second.

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Gauff, who needed courtside medical treatment between the sets, started to snatch at her shots and became too loose while Halep did what she needed to as the American racked up a total of 45 unforced errors in the match.

Gauff did save two match points when serving at 5-2 down but this time it was only a temporary reprieve as Halep finished her off in the next game.

The Romanian will now face China's Shuai Zhang in the quarter-finals and, with the bottom half of the draw looking wide open, Halep has a great chance of going on to make the final for the first time.

Gauff, who came to the tournament via a qualifying competition wildcard and ranked 313, can also expect to be challenging in the second week again in the future, and has won a legion of new fans.

Usual suspects reach men's quarters

Novak Djokovic was barely tested by Ugo Humbert. ( AP: Kirsty Wigglesworth )

In the men's draw, Novak Djokovic remained firmly in cruise control to reach the Wimbledon quarter-finals as he swatted aside France's Ugo Humbert, the latest of tennis's up-and-comers to show promise but ultimately fall short.

Djokovic, capable of jaw-dropping feats of agility when pushed to the brink, has barely stretched a sinew to reach the last eight, and the 21-year-old Humbert proved incapable of applying any real pressure in a 6-3 6-2 6-3 defeat.

It is said that youth is wasted on the young and tennis fans surveying the current crop emerging in the men's game might be inclined to agree.

With the early Wimbledon exits of the game's brightest stars — Stefanos Tsitsipas, Alexander Zverev, Auger-Aliassime and Denis Shapovalov — the hunt for a worthy successor to Djokovic, Rafa Nadal and Roger Federer seems as futile as ever.

The trio, who make up tennis's immovable oligarchy having won the past 10 Grand Slams and 53 between them, have dropped three sets in total in the opening four rounds.

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This is the first Wimbledon in the professional era when players aged 30 or over have outnumbered 20-somethings and teenagers in the men's round of 16.

The nine elder statesmen who reached this stage also equalled the record for the most men in their 30s to reach the fourth round of a grand slam, beating the record set just last month in Paris.

Djokovic will take on David Goffin in the next round after the Belgian overcame 35-year-old Spaniard Fernando Verdasco 7-6 (11-9) 2-6 6-3 6-4 to reach the quarter-finals for the first time.

The two other members of the big three barely broke a sweat in advancing.

Nadal comfortably accounted for Joao Sousa 6-2, 6-2, 6-2, while Federer beat Italian 17th seed Matteo Berrettini 6-1, 6-2, 6-2.

The only hint of a shock in the men's draw was the five-set defeat of 15th seed Milos Raonic by 26th seed Guido Pella.

The Argentinian prevailed in a bruising encounter, 3-6, 4-6, 6-3, 7-6 (7-3), 8-6.

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