World number one Naomi Osaka lost in three sets to unseeded Swiss Belinda Bencic in the Madrid Open quarter-finals on Thursday as Simona Halep, Sloane Stephens and Kiki Bertens completed the final four line-up.
Osaka, 21, admitted she over-thought about the need to win the match in order to retain her ranking at the top of the women's game as she went down 3-6, 6-2, 7-5.
The 21-year-old Japanese was a break up in the final set against Bencic, but was broken when serving for the match at 5-4 as the wind swirled despite the blue skies in the Spanish capital.
"People have been telling me that if I get to the semis I stay at number one so I wanted to do that," Osaka said.
"I wanted to do that and was thinking about it while I was playing, which wasn't a good thing. I play my best when I'm calm and today I wasn't, so that's the biggest thing I can learn."
Bencic will face two-times Madrid champion Halep in the last four after the Romanian beat ninth seed Ashleigh Barty 7-5, 7-5.
If Halep wins the tournament she will replace Osaka at the top of the WTA rankings heading into the French Open.
Stephens comfortably saw off Croatian Petra Martic 6-4, 6-3 to set up a semi-final with Bertens after the Dutch seventh seed stunned world number two Petra Kvitova 6-2, 6-3 in Thursday's late match under the floodlights.
Djokovic in semis after Cilic food poisoning withdrawal
World number one Novak Djokovic automatically progressed to the Madrid Open semi-finals after his quarter-final opponent Marin Cilic was forced to withdraw because of food poisoning on Friday.
"Dear fans, Madrid Open organisers, Novak Djokovic, I am sorry to announce that I must withdraw from today’s match," said the Croatian on Twitter.
"I have had a terrible night dealing with a case of food poisoning. I am extremely disappointed to have my time in Madrid end in this way. Thank you for the support."
Djokovic, in his 250th week at the top of the men’s ATP rankings, will face either Roger Federer or Dominic Thiem in the semi-final on Saturday.
The Serbian, who triumphed in the Spanish capital in 2011 and 2016, beat Taylor Fritz and Jeremy Chardy in the second and third rounds.