Naomi Osaka and Garbi?e Muguruza were among leading players to be knocked out of the Madrid Open on a day of upsets. (More Tennis News)

Spain's Sara Sorribes Tormo beat Osaka 6-3, 6-1 in the second round Sunday on the Spanish capital's outdoor clay courts. Four-time Grand Slam winner Osaka enjoyed six aces but had her serve broken five times by Sorribes Tormo, who had already bettered French Open runner-up Anastasia Pavlyuchenkova.

Osaka said that her movement was limited by pain in her left leg, which was heavily taped.

“I felt something in my Achilles after my last match, and like I wasn't really able to hit yesterday because I wanted it to go away,” she said. “Honestly, I probably should have been a bit smarter about the whole way that I went through everything.

“I feel like I couldn't play the way that I wanted to play, like I was limited. ... I don't even really know what I did to my Achilles, so I'm probably going to get an ultrasound and see what happened, and then me and my team will kind of move forward from there.”

Sorribes Tormo next faces Daria Kasatkina after she fought back to upset fourth-seeded Maria Sakkari 3-6, 6-3, 6-1.

Ukraine's Anhelina Kalinina brushed aside Muguruza 6-3, 6-0.?

Muguruza, the reigning WTA Finals champion, had pain in her right calf but said this wasn't the reason for her defeat.

“I was surprised with her game. I didn't know her at all,” Muguruza said. “In those break moments, they didn't work. I just let it go in (on) a couple of points.”

Bianca Andreescu beat sixth-seeded Danielle Collins 6-1, 6-1 after the American lost her serve six times and had six double-faults.

U.S. Open champion Emma Raducanu beat Marta Kostyuk 6-2, 6-1.