Miami, USA: 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, who was a set and 4-1 up in Melbourne earlier this year before losing to the Japanese star in the third round, battled superbly.
"This was a very emotional win for me," said Hsieh, whose 39 winners were one less than her opponent. "Any time you beat one of the top players it is amazing."
Osaka was coming off a fourth-round exit at Indian Wells, but Hsieh's coach said her victory wasn't all that surprising.
"She has enough experience to stay strong and you saw that," French coach Frederic Aniere, who has worked with Hsieh for the last two years and is also her boyfriend, told AFP.
"Yes it's huge, but for her it's not a big surprise."
Osaka's second-round win over Belgian Yanina Wickmayer on Friday saw a second set wobble from the two-time Grand Slam winning star and it was more of the same against Hsieh, who simply refused to give up the fight.
"I was kind of immature because I was thinking too much, like everything was on my racquet," admitted Osaka. "I got ahead of myself.
"Of course I want to win every match and I think I have dealt with people always asking me if I am going to win because I have number one next to my name," added the Japanese star.
"I thought I was doing fine with that but I guess I am not."