German fourth seed Alexander Zverev was knocked out of Wimbledon in the third round on Saturday, going down 7-6 (7/2), 4-6, 5-7, 6-3, 6-0 to Latvian qualifier Ernests Gulbis.
Her defeat means only one of the top 10 seeds has reached the last 16 in the women's draw.
She is the first women's top seed to lose to an unseeded player at Wimbledon since Ana Ivanovic lost to China's Zheng Jie 10 years ago, also just after winning the French Open.
Making 10th main draw appearance at Wimbledon, Taiwan's Hsieh Su-Wei said her relaxed approach to the season has been crucial to her progress to the fourth round for the first time.
The 14th seed from Latvia will now meet Aliaksandra Sasnovich, who reached the fourth round of a Grand Slam for the first time in her career with a 6-3 6-1 win against 26th seed Daria Gavrilova. I was fighting until the end for every ball.
'Definitely, I gave everything I had on the game side.
"I am just trying to focus on myself, every round trying to play better and improve my level, and enjoy the time on and off the court".
"I can not play my best tennis here, but I hope to improve more for the next years, to have a better result in the future".
The crowd clearly enjoyed it too.
In a sport often dominated by baseline bashers Hsieh brought so much more to the party.
The Taiwanese, who is 48th in the world rankings, came from behind to defeat Halep in a game that lasted 2 hours and 20 minutes.
"I knew what to expect, we played a lot of tough battles in the past", Kerber said of Osaka.
An inspired Hsieh claimed the last five games to post her second shock win of the year after downing Garbine Muguruza at the Australian Open. "Today's a little bit more hard". But I am too exhausted. But mentally I was exhausted.
"Inside, I was, like, dying", the 24-year-old Belgian said.
Halep, who ended her wait for a major title last month at the French Open, won the first set, had the chance to serve out for the victory and earned match point on her opponent's serve.
Halep, the French Open champion, looked like she would escape after forcing match point at 5-4 against serve in the third, but Hsieh rallied before breaking again en route to serving out the victory.