(David Ramos/Getty Images)

Another day, another upset in the women’s tennis singles at the Olympics.

Marketa Vondrousova of the Czech Republic took down No. 2 seed Naomi Osaka on Tuesday in straight sets, 6-1, 6-4.

Unlike in the first two rounds, Osaka looked out of sorts from the beginning of the match, making several mistakes and going down four games in less than 15 minutes. Eventually, the four-time Grand Slam champion won her first service game, but it wasn’t enough for her to take back momentum. Osaka lost the first set in just 24 minutes.

She battled back in the second set, but Vondrousova didn’t back down, beating Osaka with her signature drop shots.

Then, up 5-4 in the second set, the world No. 42 broke Osaka’s serve one more time to win the match.

It’s a disappointing end to a highly-anticipated return for Osaka, who was absent from both the French Open and Wimbledon due to mental health reasons.

“I definitely feel like there was a lot of pressure for this,” Osaka said after the loss, saying that this one “sucked” more than the others. “I think it’s maybe because I haven’t played in the Olympics before and for the first year (it) was a bit much.”

With the upset, five of the top 10 players in the draw are now out of contention. The highest-ranking player remaining is No. 4 seed Elina Svitolina of the Ukraine.