Naomi Osaka crashed out of the third round of the WTA and ATP Miami Open on Saturday as Hsieh Su-Wei exacted revenge for a painful Australian Open defeat with a 4-6, 7-6 (7/4), 6-3 victory.
World number one Osaka had looked in little danger after winning the first set and moving a break ahead in the second. But Taiwan's Hsieh battled superbly.
"This was a very emotional win for me," said Hsieh. "Any time you beat one of the top players it is amazing."
It wasn't the only shocker of the day, as Spanish veteran David Ferrer rallied to beat world number three Alexander Zverev 2-6, 7-5, 6-3 to reach the third round.
Ferrer, 36 and ranked 155th in the world, received a wild card into the tournament as he continues a limited schedule in a 2019 billed as his farewell tour.
The 33-year-old Hsieh will play Caroline Wozniacki in the fourth round of the women's draw, which now looks wide open following Osaka's defeat and former world number one Serena Williams's surprise exit with a left knee injury.
Elsewhere, Roger Federer survived a scare but battled back from a set down to beat Radu Albot 4-6 7-5 6-3.
"I've never really seen him play live matches so I watched some video to get an idea about him," Federer said.
"I see where he can cause problems. I have a lot of respect for those types of players who don't have the size, so have to find a different way to win. I'm happy I was able to find a way."