Naomi Osaka Upset by Unseeded Karolina Muchova, 'But Beyond Happy' with Effort

Naomi Osaka's run at the Mutua Madrid Open is over.

The World No. 2 was defeated by Karolina Muchova 6-4, 3-6, 6-1 in the second round Sunday.

Muchova is playing in just her second event since the Australian Open, where she fell in the semifinals. The weeks following the major had been marred by an abdominal injury, according to Joel Drucker of Tennis.com. 

Muchova defeated No. 1 Ash Barty en route to her Australian Open semifinal appearance.

Things quickly swung in favor of Muchova, who cracked the Top 20 rankings this week but wasn't seeded in the competition. She took an early set advantage and a 3-1 lead in the second, but Osaka rallied to win five straight games and take the middle set.

But the star couldn't keep it together, giving up a break point to Muchova in the third stage before falling 40-0 in the last game. 

Osaka chalked up the loss to her struggles on clay courts. She entered Sunday with a 59.3 winning percentage on clay, much lower than her 66.9 percentage on hard courts. 

"I'm not sure how other players play, but I'm learning that on clay I can't afford to not swing through every ball, because that automatically takes me from offense to defense," she said. "And maybe if I start being able to move better I can risk starting to play on defense, but as of right now I think I should be the aggressor." 

Muchova will face Greece's Maria Sakkari in the round of 16.