Fifth seed Garbine Muguruza was dumped out of the Madrid Open in miserable fashion on Sunday, going down 6-1 6-3 to Timea Bacsinszky just three weeks before the start of her French Open defence.
Whistles could be heard from the crowd as Muguruza, who has struggled for form in 2017, bowed out at the first hurdle with a double fault.
The Spaniard twice lost six games in succession during a one-sided encounter as Switzerland's Bacsinszky, the world number 27, set up a second-round meeting with Kiki Bertens.
There were no other major shocks on Sunday, with top seed Angelique Kerber and reigning champion Simona Halep, as well as Dominika Cibulkova, Svetlana Kuznetsova and Maria Sharapova, all progressing.
However, Sharapova - the 2014 winner in Madrid - was forced to come from a set down before beating Mirjana Lucic-Baroni 6-0 in the deciding set of their contest and Jelena Jankovic served for the match against Cibulkova, only for the Slovakian to prevail 6-4 5-7 7-5.
SHARAPOVA-BOUCHARD MONDAY'S HEADLINE ACT
Eugenie Bouchard caused quite the stir with her comments about Sharapova last week as the Russian made her return from a 15-month doping ban, and, as fate would have it, the two are now set to go head-to-head in Madrid.
Sharapova's hard-fought victory over Lucic-Baroni ensured she will face Bouchard in a Monday evening encounter that is sure to attract plenty of attention.
KERBER EARNS WELCOME WIN
World number two Kerber had lost her last four matches at the Madrid Open ahead of her first-round clash with Timea Babos.
However, the German ended that barren run with a degree of comfort, winning 6-4 6-2 on Sunday.
"It's now a very good feeling because the last three years I lost here in the first round," said Kerber.
"It was not the best tournament I played, that's true.
"Maybe [it will] change this year."
PLISKOVA PUMMELLED AFTER QUICK TURNAROUND
Kristyna Pliskova could hardly have asked for a tougher test as she faced defending champion Halep just 24 hours after losing the final of the Prague Open on Saturday.
The Czech was comprehensively beaten, 6-1 6-2, and received sympathy from her opponent.
Halep said: "She [Pliskova] did great in Prague. She came yesterday. Maybe she didn't have time to get used to this court. But I wanted to do my job from the beginning. I think I did pretty well, I finished strong."
WOZNIACKI, CIBULKOVA WIN GRUELLING BATTLES
If Sharapova's three-set match proved a stern examination, Caroline Wozniacki faced an even tougher test before finally booking her place in round two.
Wozniacki needed almost three and a half hours to battle past Monica Niculescu 7-5 6-7 (3-7) 6-4.
Cibulkova, meanwhile, was pushed all the way by Jankovic, before winning the last three games of a final set lasting 65 minutes.
That was a battle out there today! 3h 27min.. Happy to be thru to the next round pic.twitter.com/nY4uUlFwWM— Caroline Wozniacki (@CaroWozniacki) May 7, 2017