Naomi Osaka launches her bid for a third US Open title in four years on Monday, aiming to put turmoil behind her as she chases her second Grand Slam title of 2021.

Osaka, who rocketed to fame when she beat superstar Serena Williams in the 2018 US Open final, appeared set for a sparkling 2021 campaign after she beat American Jen Brady in the Australian Open final in February to capture her fourth major crown.

But she has played sparingly since, pulling out of the French Open after she was fined for failing to meet mandatory media requirements.

Osaka, who said she believed post-match news conferences were detrimental to her mental health, opted out of Wimbledon as well, and after the magical moment of lighting the cauldron at the Tokyo Olympics bowed out in the third round.

Although she also lost in the third round at Cincinnati in August, Osaka said she was "pretty happy" with her game heading into the high-pressure atmosphere of the Billie Jean King National Tennis Center in Flushing Meadows.

As she looked ahead to her Monday opener against Czech Marie Bouzkova Osaka said in a social media post that she wants to start to savor her accomplishments and let go of negative thoughts.

"Recently I've been asking myself why do I feel the way I do and I realize one of the reasons is because internally I think I'm never good enough," she wrote. "I never tell myself that I've done a good job, but I do know I constantly tell myself that I suck or I could do better.

"Seeing everything that's going on in the world I feel like if I wake up in the morning that's a win," Osaka wrote. "Your life is your own and you shouldn't value yourself on other people's standards. I know I give my heart to everything I can and if that's not good enough for some then my apologies but I can't burden myself with those expectations anymore."

Osaka has already acknowledged that it will take some adjusting after last year's spectator ban to adjust to the return of fans to the 23,771-seat Arthur Ashe Stadium.

Crowds at the normally rowdy Open will be back at full capacity, although organizers announced last week that all attendees will be required to provide proof of having received at least one Covid-19 vaccination.

With world number one Novak Djokovic waiting in the wings, second-ranked Daniil Medvedev closes out the action on Ashe on Monday against French veteran Richard Gasquet.

Play opens with former women's champion Sloane Stephens taking on Madison Keys in an All-American clash.

Murray v Tsitsipas

Then former champion Andy Murray faces a daunting challenge as he continues his return from his latest injury as he goes up against third-seeded Stefanos Tsitsipas of Greece.

"Not the easiest draw out there," Murray, whose 2012 US Open triumph was the first of his three Grand Slam victories, said.

"When you're not seeded, these sorts of things can happen," Murray said, adding that he thought the New York crowd could help him.

"They like people that fight, give their all, show their heart and emotion and energy on the court," he said.

Elsewhere on Monday, former world number one Victoria Azarenka -- who fell to Osaka in last year's final -- takes on Czech Tereza Martincova on Grandstand court.

Also on Grandstand Simona Halep, who was forced out of her Wimbledon title defense with a calf injury, takes on Italian Camila Giorgi.

Women's second seed Aryna Sabalenka of Belarus faces Serb Nina Stojanovic to open the night session on Louis Armstrong court, where rising US star Coco Gauff anchors the day session and mercurial Australian Nick Kyrgios brings down the curtain against Spain's Roberto Bautista Agut.