Naomi Osaka came out on top when she dreamed of playing Serena Williams in a grand slam final and will now get the chance to earn the same outcome in reality at the US Open.

Osaka set up a fascinating showdown with 23-time grand slam champion Williams, who she has idolised since she was a young child, by beating Madison Keys at Flushing Meadows on Thursday.

Japan's first female slam finalist told a news conference: "Of course it feels a little bit, like, surreal. Even when I was a little kid, I always dreamed that I would play Serena in a final of a grand slam.

"Just the fact that it's happening, I'm very happy about it."

Asked how the match played out in her dreams, a laughing Osaka replied: "You already know.

"I don't dream to lose, so ... that's how I'm answering your question."

Although the 20-year-old holds Williams in the highest regard, she is confident she can focus on the job at hand on Saturday, as she did when beating Williams in Miami earlier this year.

"I felt sort of similar [then] to how I feel now," she added. "I'm very hyped for it, but when I stepped onto the court, I just thought it was another match."

That contest came early in Williams' comeback after the birth of her first child and Osaka knows she is likely to face a much sterner test this time around.

"I think that experience was really good for me," said the Japanese. "Of course, I feel like since the circumstances were so different, I'll be able to see how she's changed.

"Of course I feel like I'm a challenger. She's been in so many grand slam finals, she knows how it feels. I'm still really new.

"For me, that's the fun part. I think I'm going to really embrace the moment and I'm going to play to the best of my abilities."