Naomi Osaka's 23-match winning streak came to a crashing halt Wednesday as Japan's world No. 2 was stunned 6-0, 6-4 by Maria Sakkari in the quarterfinals of the Miami Open.

Japan's Osaka, playing her first tournament since lifting her fourth Grand Slam title at the Australian Open in February, won just eight points in the first set, failing to manage a single winner.

Osaka broke in the second game of the second set and seized a 3-0 lead before Sakkari roared back to seal a semifinal spot in the prestigious ATP Masters and WTA hardcourt tournament.

The defeat ended Osaka's chance of overtaking top-seeded Australian Ashleigh Barty atop the world rankings this week, a fact she acknowledged may have upped the pressure she was feeling against Greece's 25th-ranked Sakkari.

"It's hard to say," she said of whether that made a difference in the match. "The last time I was in this [press conference] seat, I wasn't really thinking at all about rankings, but someone asked me that question, so then I did start to ponder about it a lot."

"So maybe unwillingly that put pressure on myself. But I feel like even if it did, I should be able to rise above that," she added. "This is definitely something that shouldn't bother me as much as it did."

"To be deadly honest, I got a little tight in the first two games of the second set," Sakkari said. "I had two break points and didn't take them, then a bad service game, which can happen. I stayed within myself and started fighting back, hitting a few more balls and winning a few points against her."

Sakkari next faces either Canadian eighth seed Bianca Andreescu or Spain's Sara Sorribes Tormo.

Men's quarterfinal action got underway at the Hard Rock Stadium with top-seeded Daniil Medvedev taking on seventh-seeded Roberto Bautista Agut.

The Spanish veteran has won both prior encounters with Medvedev, who was runner-up to Novak Djokovic at the Australian Open and reached No. 2 in the world with his victory at Marseille in March.

The winner of that match will take on either 21st-seeded Italian Jannik Sinner or 32nd seed Alexander Bublik of Kazakhstan.