(CNN) — Women's world No.1 Ashleigh Barty couldn't maintain her French Open-winning form and crashed out of Wimbledon to American Alison Riske in the fourth round Monday.
The Australian lost 6-3 2-6 3-6 to the 29-year-old Riske, ranked 55th in the world, in one hour 37 minutes on Court No.2.
Riske's previous best grand slam result was a fourth-round defeat at the 2013 US Open.
The shock result kicked off Wimbledon's blockbuster "Manic Monday" when all 32 remaining men's and women's singles players compete for a place in the quarterfinals.
Cori "Coco" Gauff -- the 15-year-old sensation who has taken this grand slam by storm -- continues her remarkable fortnight but faces one of the pre-tournament favorites in Simona Halep, a former world No.1.
The "Big Three" in the men's game, Novak Djokovic, Rafael Nadal and Roger Federer, all face tricky ties but it's the Swiss who has arguably the toughest day.
Eight-time champion Federer is up against talented Italian youngster Matteo Berrettini, seeded 17th at the All England Club, who has already overcome the tests of Diego Schwartzman and Marcos Baghdatis.
Third seed Nadal opens proceedings on Centre Court against Portugal's Joao Sousa, while defending champion Djokovic plays French 21-year-old Ugo Humbert in the third match on No.1 Court.
First up on No.1, seven-time Wimbledon champion Serena Williams will face diminutive Spaniard Carla Suarez Navarro.
And home favorite Johanna Konta -- the only Briton remaining in the draw -- faces No. 3 seed and former Wimbledon champion Petra Kvitova.
Riske said she was "proud" of herself for reaching the quarter finals for the first time.
"I've been ready to battle every day that I go out there and that's really shown in all my matches," she told BBC Sport.
"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. 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'."
This story was first published on CNN.com, "Ashleigh Barty knocked out of Wimbledon on 'Manic Monday'"