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Daria Kasatkina reacts after scoring a point against Irina-Camelia Begu Thursday, April 5, 2018 at the Volvo Car Open on Daniel Island. Kasatkina won 6-2 and 6-1. Andrew Whitaker/Staff

Daria Kastkina said she felt like she was "flying." Naomi Osaka looked like she had been crying.

The pair of rising stars on the WTA Tour, both 20 years old, shared a private jet to Miami last month after Osaka beat Kasatkina in the finals at Indian Wells.

But on Thursday, they found themselves in much different places after the third round of the Volvo Car Open on Daniel Island.

Kasatkina, the defending VCO champ, cruised into the quarterfinals with a straight set victory, as did top American seed Madison Keys.

"I think I was almost flying," Kasatkina said after a 6-2, 6-1 rout of No. 13 seed Irina-Camelia Begu.

Osaka confessed to being "depressed" after a 7-6, 6-3 loss to No. 5 seed Julia Georges of Germany.

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Naomi Osaka shows her frustration during her match against Julia Goerges on April 5 at the Volvo Car Open on Daniel Island. Andrew Whitaker/Staff

Top-seeded Caroline Garcia could empathize with Osaka after she was eliminated by fellow Frenchwoman Alize Cornet in Thursday's late match. The No. 14 seed Cornet won by 5-7, 6-1, 6-4.

Osaka has had quite the rocket ride to fame in recent weeks, beating the likes of Maria Sharapova, No. 1 Simona Halep and legend Serena Williams.

She upset five-time major champ Sharapova and three other Grand Slam finalists without dropping a set en route to her first WTA Tour title at Indian Wells, where she cashed a check for $1.34 million, and pushed her ranking to a high of No. 19.

All of that seemed to catch up with her Thursday. Osaka appeared near tears on her cart ride back to the players' clubhouse, and later confirmed that she's had a difficult time this week.

"What I felt today was a new feeling, though," said Osaka, the daughter of a Haitian father and Japanese mother who moved to the U.S. to train when she was three. "Like, what I felt today I've never felt it before."

Osaka then found a word for what she felt: "Depressed."

"I don't know how to explain it, but like kind of depressed, but like it comes in waves," she said. "... Like yesterday, I just woke up and I was really depressed, but I don't know why."

Having played three straight tournaments in Indian Wells, Miami and Charleston, Osaka is ready for a break and a chance to come to grips with her new place in the game.

"Nothing," she said when asked what she wants to do next.

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Julia Goerges returns the ball against Naomi Osaka Thursday, April 5, 2018 at the Volvo Car Open on Daniel Island. Goerges won 7-6(4) and 6-3. Andrew Whitaker/Staff

Georges, a 29-year-old German veteran who is ranked No. 13, knows what Osaka was feeling.

Down 5-3, Goerges held for 6-6 with an ace and three service winners, then won the tiebreak with her fourth ace.

"I saw that her body language changed in the second set," Goerges said of Osaka. "She was, I think, a little bit frustrated that she couldn't take the opportunities she had in the first set, and she really let me back in."

Kasatkina and Keys, a finalist at the U.S. Open last year, had little trouble in their stadium court matches.

"I'm really happy about it because I was really stretched in my first match," Kastkina said. "But I hope this pressure disappears.

"... Nobody told me it was so difficult to come and defend a title. So I have to get used to it."

No. 8 Anastasija Sevastova topped No. 9 Ashleigh Barty, 6-3, 6-4 to make the quarters, and No. 12 Kiki Bertens got past qualifier Fanny Stollar by 6-2, 6-4.

Friday's Quarterfinals

11 a.m. on Stadium Court

No. 5 Julia Goerges vs. No. 3 Daria Kasatkina

Bernarda Pera vs. No. 7 Madison Keys

No. 8 Anastasija Sevastova vs. Kristyna Pliskova

Not before 7 p.m.

No. 14 Alize Cornet vs. No. 12 Kiki Bertens

Reach Jeff Hartsell at 843-937-5596. Follow on Twitter @Jeff_fromthePC