Madrid - Two-time champion Simona Halep overcame Ashleigh Barty 7-5, 7-5 to reach her fourth Madrid Open semi-final on Thursday.
Romania's third seed and former number one will next play the winner from top seed Naomi Osaka and on-form Swiss Belinda Bencic.
Halep, who has been struggling with injury, took the opening set and went up a break in the second before losing it against the ninth-seeded Australian who won the Miami title in March.
Halep regained control with a break for 6-5 as her opponent returned wide. She wrapped up victory with an untouchable forehand to the corner.
"It's not easy to keep winning here," Halep said after a victory in which she broke four times.
"But I'm very motivated after reaching the semi-finals again. I will have another challenge tomorrow (Friday), so I'm not looking any further ahead than that.
"If I can play my best tennis, then we will see," added the player who advanced through her third-round match on Wednesday without the loss of a game.