INDIAN WELLS, CA, USA - Japan's Naomi Osaka claimed the first title of her promising WTA career on Sunday afternoon on a big stage at the BNP Paribas Open, as she prevailed in a battle of 20-year-olds against Russia's Daria Kasatkina, 6-3, 6-2.

After being broken in the opening game of the match behind a misfiring forehand, Osaka settled in and imposed her will on the first career meeting between two of the WTA's brightest young stars, and won nine of the last 11 games against the No.20 seed to win the first Premier Mandatory event of the season.

As it happened: Osaka crowned in desert at BNP Paribas Open

With the win, Osaka is first player to win her first WTA singles title at Indian Wells since Slovakia's Daniela Hantuchova in 2002, and the third unseeded champion after Serena Williams (1999) and Kim Clijsters (2005).

She is the sixth different champion in the desert in the last six years, and is also the sixth different champion in the past six Premier Mandatory events.

"I was extremely stressed and extremely nervous, but my plan was to fake that I'm very calm," Osaka spoke candidly after the match. 

"I just knew that she was going to fight for every point, too, so I couldn't afford to lose points based on nerves, and I had to keep making the right decisions."

Kasatkina was the beneficiary of four forehand unforced errors off Osaka's racquet in the opening game, as the Russian built a 0-40 lead and eventually broke on her third opportunity to begin the match.

However, the Japanese quickly shook off her early nerves to break back in the second game, and got her serve firing. Staying ahead for the duration of the match from there, faced just one break point the rest of the way - in the seventh game of the opener.

She duly saved Kasatkina's chance, and later took advantage of the Russian's misfiring forehand to nab her second break, and move into a one-set lead after 40 minutes behind a pair of crunching backhands. 

"It was hard for me to get my nerves in check in the first game, especially since -- I don't know why I decided to serve first," Osaka added. "We were playing some long points, and I wasn't really trying to hit hard today, because I felt like it would be better for her to take my pace.

"I wanted her to do whatever she wanted to do, and I was just going to sit back and see what she does. I feel like I wasn't that aggressive today. I was just more consistent."

The Russian, who also had her share of notable wins in the fortnight against Grand Slam champions Sloane Stephens, Caroline Wozniacki and Venus Williams, could do little to recapture that magic over the course of nearly 71 minutes of play. 

Osaka broke again in the first game of the second set, and added a second for insurance in the fifth en route to the straight-set victory, dropping just three points behind her own serve in the process in the entire set.

"Basically she was much better today than me, so she really deserved to win," she said. "I think we were both nervous at the beginning, because [this was our] biggest finals so far. During the match, she was able to manage her nerves and stuff, and I was still a little bit tight.

"She's very powerful. She's playing, serving good, and doesn't have weaknesses. She's hitting her forehand, backhand, so she's really tough."

Already the youngest finalist at the BNP Paribas Open (20 years and 153 days) since Caroline Wozniacki (19 years, 253 days) finished runner-up in 2010, Osaka is also the youngest champion in Indian Wells since Ana Ivanovic (20 years, 138 days) raised the trophy exactly a decade ago in 2008.

The current World No.44, who defeated Maria Sharapova, Agnieszka Radwanska, Karolina Pliskova and World No.1 Simona Halep en route to reaching her second career singles final, will rise to a new career-high of World No.22 in Monday's rankings. 

"I really wanted to win this, but also I just tried to think it was a first-round match and just not psych myself out too much," she concluded. "I don't really know what's going on right now. I really feel like I have another match I have to play tomorrow, and it didn't really sink in that I won. I'm happy."