French Open champion Jelena Ostapenko's preparations in the run-up to the claycourt major hit the skids in the first round of the Madrid Open on Saturday as she was beaten 6-3 6-3 by unseeded Romanian Irina-Camelia Begu.
The Latvian has failed to scale the same heights she reached last year when she emerged out of nowhere to conquer Roland Garros.
But if the 20-year-old harbours any hopes of repeating that run in Paris later this month, she will have to make a vast improvement on Saturday's error-filled performance.
Joining her at the exit was American Venus Williams, a runner-up in Madrid in 2010. She was beaten 3-6 6-3 6-2 by Estonian Anett Kontaveit.
World number four Elina Svitolina and former world number one Karolina Pliskova, however, eased to victories.
Ukrainian Svitolina, the fourth seed, struck 28 winners and lost her serve just once as she brushed Alize Cornet aside for a 6-2 6-2 victory.
Svitolina is aiming to win her third title of the year but the 23-year-old has never progressed past the second round in Madrid.
Sixth seed Pliskova, coming off a Stuttgart Open title win last month, extended her winning run to six matches after striking 29 winners and seven aces to sweep past Elena Vesnina 6-4 6-2.
"I think I could play much better. Some parts were good, but my concentration was up and down. Sometimes, after you win a tournament you feel like everything is going to be easy, and I wasn't fighting like I was in Stuttgart," Pliskova said.
"That's what I want to improve because my next match will be very tough."
The duo will be joined by French seventh seed Caroline Garcia and Russian Daria Kasatkina in the next stage.
American 12th-seed CoCo Vandeweghe's defeat by unseeded Frenchwoman Kristina Mladenovic was the other upset of the day.
World number one Simona Halep, Race to Singapore leader Caroline Wozniacki and Spaniard Garbine Muguruza will take to the courts for their first round matches on Sunday.
(Reporting by Aditi Prakash in Bengaluru, editing by Pritha Sarkar)
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