Osaka was eliminated in the first round of the US Open

Osaka is a four-time Grand Slam champion and winner of Flushing Meadows in 2018 and 2020, 7-6 (7-5) 6-3 at the hands of 19th-seeded American Collins in a battle between two top hitters.

Collins, a finalist at this year’s Australian Open, advances to the second round to face Spain’s Cristina Boxa.

The 28-year-old right-hand man from Florida will head into the task full of confidence after showing great composure to keep Osaka away from Arthur Ashe Stadium.

No one was more surprised by this victory than Collins, who missed tournaments in Silicon Valley and Toronto to allow herself time to recover from a neck injury.

“I’m still really speechless because I’m taking summer vacation,” Collins said. “To get out here, play a strong contender in the first round, someone who has won two Grand Slam titles here, it’s not easy.

“Just going to the moon about being able to get through this first round because I don’t think most guys want to face Naomi in the first round.”

Former world number one Osaka, whose ranking slipped to 44 after an uncertain year, got off to a smooth start with an early break to lead 3-0.

But Collins fought back in the match and took the first set with a hard-earned victory.

With both players doing some booming ground strikes, the second set was about who would blink first.

Collins set herself on the winning streak after breaking Osaka to lead 5-3 in the eighth inning.

Osaka, 24, came within walking distance of the break needed to keep the game alive after leading 15-40 in the ninth game.

But Collins scored again and then snatched the win on her first point when Osaka scored a long comeback.

Osaka later said she was troubled by a back problem.

“I tried as hard as I could. I wanted to play without hurting my back. I really only started a couple of days ago,” she said.