Naomi Osaka moved into the Miami Open semi-finals with another impressive performance as an out-of-sorts American Danielle Collins was brushed aside at the Hard Rock Stadium on Tuesday.

The clinical Japanese star, yet to drop a set in this tournament, won 6-2, 6-1 and will meet Swiss Olympic gold medal winner Belinda Bencic in the last four.

Collins, who appeared to be struggling with a neck injury and has been suffering with a viral infection, will return to the top 10 when the rankings are released on Monday having briefly been there following her run to the Australian Open final earlier this year.

But Osaka, the four-time Grand Slam champion, has been in fine form in south Florida and on this evidence will take a lot of stopping if she is to be denied the title this weekend.

"I hope she is ok," said Osaka after her victory over the struggling Collins.

"This was my first night match so I didn't know what the conditions were like but I was fine and the fans were great," added Osaka who hit 12 aces in a match that lasted exactly one hour.

Bencic, the world number 28, who beat Australia's Daria Saville 6-1,6-2, said: "I have played Osaka before, so I know how it feels to play her.

"I'm really happy I achieved a great result here and everything else is a bonus. I'm going to enjoy and do the best I can."

In Wednesday's remaining WTA quarter-finals, American Jessica Pegula will play Spain's Paula Badosa while Czech Petra Kvitova takes on world number one Iga Swiatek of Poland.