Naomi Osaka said her Indian Wells Masters triumph was still sinking in after the Japanese sensation claimed her maiden WTA Tour title on Sunday.

Osaka blitzed Daria Kasatkina 6-3 6-2 in the battle of the 20-year-olds for the biggest victory of her short career.

World number one Simona Halep and five-time grand slam champion Maria Sharapova were swept aside by Osaka en route to the decider and the unseeded Japanese star ended a dream week in emphatic fashion.

"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," Osaka said.

"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."

Osaka (20 years, 153 days) is the youngest Indian Wells champion since Ana Ivanovic (20 years, 138 days) lifted the trophy in 2008.

She is also the third unseeded champion at the tournament, following in the footsteps of Serena Williams (1999) and Kim Clijsters (2005).

Reflecting on her victory over Kasatkina, who stunned Australian Open champion Caroline Wozniacki, Angelique Kerber and Venus Williams during the event, Osaka said: "I was extremely stressed and extremely nervous, but my plan was to fake that I'm very calm. 

"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."