Naomi Osaka secured a long-awaited victory over a top-10 opponent after dispatching Jelena Ostapenko at the US Open on Tuesday.

World number 88 Osaka scored a 6-3 6-2 victory against Ostapenko for her first top-10 win in four-and-a-half years.

Osaka has now won 23 of her 28 matches at the US Open, at an 82% win ratio, which only Bianca Andreescu (86%) can better among current players with 10 or more main-draw matches at the tournament.

The four-time major winner was reduced to tears after downing the 10th seed in New York.

"I was trying not to cry when I was walking out too," Osaka said in her on-court interview. "I remember last year I was watching Coco [Gauff] play and I so badly wanted to step on these courts again and I didn't know if I could.

"I didn't know athletically, physically if I was able to. Just to win this match and just to be in this atmosphere means so much to me, so thank you."

Osaka, who won 39 of her 50 service points and held her serve throughout, needed three match points to move into the second round.

"I mean it was stressful, she was hitting some really good shots and I just told myself like, keep going, keep fighting for every point and maybe you'll have an opportunity," she added. 

"Eventually I did but then I looked up and then I saw so many faces so I was like, woah."

The unseeded Karolina Muchova awaits on Thursday for the Japanese star after her first-round triumph.