World number one Naomi Osaka's bid for a third straight Grand Slam ended at the hands of unseeded Czech Katerina Siniakova at the French Open.
Osaka, 21, lost 6-4 6-2 to the world number 42 in their third-round match.
The Japanese top seed made 38 unforced errors as she lost in one hour and 17 minutes at Roland Garros.
"It is incredible, it is something I can't believe, I'm so happy," Siniakova said after reaching the last 16 of a Grand Slam singles for the first time.
The 23-year-old right-hander is ranked as the world's leading women's doubles player and won that competition at the French Open last year alongside fellow Czech Barbora Krejcikova.
"Roland Garros brings out my best and I hope it will continue," she added.
Siniakova will play either American 14th seed Madison Keys or 20-year-old Russian Anna Blinkova for a place in the quarter-finals.
US Open and Australian Open champion Osaka looked strangely subdued on a sun-basked Court Suzanne Lenglen, the backing of the Paris crowd unable to rouse her.
A double fault on break point at 4-2 in the second set summed up her troubles, drawing gasps from the spectators and leaving Siniakova with the chance to serve for the match.
More errors from Osaka's racquet - a wild backhand whacked well long, a weak forehand into the net then another backhand wide - brought up two match points for her Czech opponent.
And she only needed one as Osaka hit another forehand past the baseline.
Siniakova jumped up into the air with both fists clenched, turning and screaming in delight at her box, before Osaka greeted her at the net while nodding in appreciation of the performance.