Naomi Osaka has pulled out of the Western & Southern Open final because of a left hamstring injury, giving the title to Victoria Azarenka in a walkover.
"I just hope I'm giving myself, you know, the opportunity and the chance to have enough time" to recover ahead of the US Open, Osaka said.
The grand slam tournament, which she won in 2018, starts on Monday.
Osaka's decision to skip the final was announced about 90 minutes before the championship match was supposed to begin in Louis Armstrong Stadium - at the site of the US Open.
The Western & Southern Open normally is held in Ohio but was moved to New York this year because of the coronavirus pandemic as part of a two-tournament "controlled environment".
Osaka said she initially felt a problem with her leg in her first match of the Western & Southern Open and pulled the hamstring in the second-set tiebreaker of her 6-2, 7-6 (7-5) semifinal win over Elise Mertens.
Osaka grabbed her left hamstring after chasing a ball early in the tiebreaker.
On Saturday, she called this an "emotional week".
Osaka, a 22-year-old who was born in Japan and is now based in the US, brought the push for racial justice to the tennis tour by saying she was not going to play in her semifinal, joining athletes in the NBA, Major League Baseball and other sports in sitting out this week in reaction to the police shooting in Wisconsin of a black man, Jacob Blake.
Osaka's stance prompted the tournament to say it was taking a "pause" to back the cause and scrapping all scheduled matches for Thursday.
When play resumed on Friday, Osaka did compete.
The 59th-ranked Azarenka collects her first title since 2016 and the 21st of her career, 20th at a hard-court event.
She is a two-time Australian Open champion, two-time US Open runner-up and has been ranked as high as No. 1.
"It's unfortunate, because I was actually really looking forward to compete against Naomi. It would have been an amazing opportunity to face her level," said Azarenka, who also won the Western & Southern Open in 2013.
Azarenka said the title was "special" because it's her first as a mother.
The 31-year-old Azarenka considered retiring at the start of the year.