Japan’s Naomi Osaka withdrew from the Western & Southern Open WTA final due to a left hamstring injury on Saturday, just two days before the start of the US Open.

The world No 10’s withdrawal means meaning Victoria Azarenka takes the title by walkover.

“I’m sorry to have to withdraw today with an injury,” said Osaka, who is currently on the Monday night schedule at the US Open where she is due to play fellow Japanese player Misaki Doi in first round.

“I pulled my left hamstring yesterday in the second set tiebreak and it has not recovered overnight as I had hoped.”

Osaka, 22, had defeated Belgium’s Elise Mertens in the semi-final to set up the championship match against two-time Australian Open winner Azarenka, from Belarus, in the same New York Covid-19 quarantine bubble where the US Open will be held.

Two-time Grand Slam champion Osaka, of Haitian and Japanese heritage, had threatened not to play in the semi-finals to protest the police shooting of African-American Jacob Blake in Kenosha, Wisconsin.

Osaka said she was “sick to her stomach” and “exhausted” by repeated violence against blacks by US police, echoing a move by the NBA Milwaukee Bucks in boycotting a playoff game for the same reason, which brought the entire league to a standstill for three days.

Osaka’s decision prompted the WTA and ATP to postpone all semi-final matches to Friday, which inspired Osaka to change her mind and play, although she was worried other delayed players would be upset.

“This has been an emotional week and I want to thank everyone for the outpouring of support,” said Osaka, who had said on Friday her gesture, and the backing she received from the tours and other players had made her “more aware of the impact my voice could have.”

The injury, however, is a major blow as she prepared to the return of her first Grand Slam triumph, her 2018 victory over US star Serena Williams in a controversial US Open final at the National Tennis Center in Flushing Meadows.

She followed that up with a victory in the 2019 Australian Open before enduring a slump that saw her exit in the first round of Wimbledon and exit early in her defense of the US Open title.

With her father standing in as coach Osaka roared back to the form that had made her number one with back to back titles in Japan and China in 2019.

In May she was reported by Forbes to be the highest paid female athlete in the world, the magazine calculating her earings over the prior 12 months at $37.4 million (34.3 million euros).

She edged Williams by $1.4 million in prize money and endorsement income over the past year.

But Osaka endured disappointment again at the Australian Open in January, where she fell in straight sets to unseeded US teenager Coco Gauff in the round of 32.

She had lost in the semi-finals at Brisbane in an Aussie Open tune-up event, and the Western & Southern Open was her first WTA appearance since the tour resumed in the wake of a coronavirus shutdown that started in March and caused Wimbledon to be cancelled and the French Open postponed to late September.