AFP - Japan's Naomi Osaka came from a set down to beat Victoria Azarenka of Belarus to win the US Open on Saturday and clinch her third Grand Slam title.

Osaka, the fourth seed, overcame her unseeded opponent 1-6, 6-3, 6-3 inside a near-empty Arthur Ashe Stadium at Flushing Meadows.

It brought the 22-year-old's haul of tennis major trophies to three after her victories at the 2018 US Open and 2019 Australian Open.

"I didn't really enjoy that. It was a really tough match for me," Osaka said following her 1hr 53min victory.

Azarenka, 31, sprinted to the first set in just 26 minutes, dominating Osaka with an 88 percent success rate on her first serve.

The Japanese was uncharacteristically sloppy, hitting a whopping 13 unforced errors.

The Belarusian then went 2-0 ahead in the second set before Osaka fought back to break her opponent's serve twice and take a 4-3 lead.

The momentum had quickly swung in Osaka's favour and she broke a third time to take the match to a deciding set.

Osaka enjoyed the first breakthrough of set three in game four when she broke Azarenka's serve to take a 3-1 lead.

Azarenka then blew a golden opportunity to get back into the match, wasting three break points as Osaka recovered from 0-40 to hold for a 4-1 lead.

Azarenka saved four break points to make it 4-2 as she battled to keep the contest alive and when she broke Osaka in game seven, the set was back on serve.

But Osaka immediately broke back after Azarenka pushed a forehand wide to leave herself the opportunity of serving for the match and title.

On Osaka's second championship point, Azarenka found the net.

After touching racquets with her opponent, Osaka lay down in the middle of the court and looked up at the sky in celebration.

"I always see everyone sort of collapse after match point. But I always think you may injure yourself so I wanted to do it safely," Osaka said.

The match was watched by just a few dozen people, mostly officials, journalists and event staff after the coronavirus pandemic forced the tournament to be held behind closed doors.

Osaka had walked onto the court wearing a mask bearing the name of Tamir Rice, a 12-year-old African-American boy who was shot dead by a white police officer in Cleveland, Ohio in 2014.

Main picture: Osaka (R) with her US Open trophy, next to runner-up Azarenka (AFP)