On a recent Sunday afternoon, a pair of 20-year-olds boarded a private jet for the first time, preparing for a cross- country flight, southern California to Miami.

They were about as giddy as you'd expect a pair of 20-year-olds to be.

Naomi Osaka wondered if her fellow passenger, Daria Kasatkina, would talk to her on the flight. After all, Osaka had just beaten Kasatkina in the finals at Indian Wells for her first WTA Tour victory.

Would it be, like, awkward?

"I don't know what you're supposed to say to someone that you've not really talked to before," Osaka fretted. "So it's not like I have a certain conversation. I just think it would be really cool to talk to her.

"I'm so weird. It's so bad. Oh my God. OK."

As it turned out, the flight passed uneventfully. No post-match squabbles broke out, and Kasatkina sat a couple of rows in front of Osaka, the two speaking only in passing.

Learning the etiquette of private jets is just one part of the on-going tennis education of Osaka and Kasatkina, two breakout stars of the WTA Tour as the women's professional tennis circuit heads to Daniel Island for the Volvo Car Open this week.

Kasatkina, a 5-7 Russian, used her breakthrough victory at last year's Volvo Car Open as a springboard to what's been a brilliant 2018 season thus far. She beat four Grand Slam champions — Sloane Stephens, Caroline Wozniacki, Angelique Kerber and Venus Williams — on the way to the Indian Wells final. She's perched just outside the top 10 at No. 11.

+2 
Volvo Car Open

Daria Kasatkina holds up the Volvo Car Open trophy after defeating Jelena Ostapenko during the final match on Sunday, April 10, 2017. Kasatkina defeated her opponent 6-3 and 6-1. Brad Nettles/Staff

Osaka, a 5-11 right-hander born of a Japanese mother and Haitian father, is making her fourth appearance in Charleston. Last year, she lost to hometown favorite Shelby Rogers in the round of 16. Her road to the finals at Indian Wells included wins over Maria Sharapova, No. 5 Karolina Pliskova and No. 1-ranked Simona Halep. She's rocketed from No. 68 at the end of 2017 to No. 22.

Both players appeared several years ago on the keen radar of Volvo Car Open tournament director Bob Moran, who relishes the tournament's reputation as a launching pad for new stars.

"I remember talking to a coach who told me, 'This young girl from Japan, Osaka, is somebody you need to pay attention to,'" Moran said. "She's got a big game, and it might take her a little bit. But she's gonna be one to watch.

"So we immediately reached out to her to get her to Charleston, and it was the same story with Kasatkina."

Osaka knocked off her idol, new mom Serena Williams, last week in Miami, gushing about how cool it was to see Serena in person (and not on TV), and to shake her hand after the match.

"It was a dream come true," Osaka said from Miami this week. "I grew up watching and idolizing Serena, so it was an honor to share the court with her. To win was even more special."

Osaka, who was born in Japan but moved to Florida at age 3, is a refreshing presence in post-match press conferences. She peppers interviews with references to "Caveman Spongebob" and has been candid about her need for wheat toast for breakfast and not sourdough — definitely not sourdough.

"I'm not really sure," she said when asked where her sense of humor comes from. "My parents aren't very funny. I kind of think I got it from the internet."

Osaka is sure to have a higher profile among Charleston fans at the Volvo Car Open than she did last year, but so far has taken her new fame in stride.

"Not at all," she laughed when asked if success has changed Naomi Osaka. "I still have a long way to go on this road, and I'm just getting started."

Who knows? Maybe she'll one day have her own private jet.

5 More to Watch

1. Sloane Stephens

The 2016 VCO champ was forced to the TV booth by injury last year — then recovered to win the U.S. Open. Oh by the way, she also won at Miami on Saturday.

2. Petra Kvitova

The 2-time Wimbledon champ is making her VCO debut, part of her remarkable comeback from a hand injury suffered in a 2016 home invasion.

3. Madison Keys

The 23-year-old American made the VCO finals in 2015, and lost to Stephens in the U.S. Open finals last year.

4. CiCi Bellis

Bellis is making her Charleston debut at age 18, and was named the WTA Tour Newcomer of the Year in 2017.

5. Bethanie Mattek-Sands

Paired with Lucie Safarova to win the VCO doubles title last year, then suffered an awful knee injury at Wimbledon. The 32-year-old American is on the comeback trail.

 

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