NEW YORK -- Naomi Osaka walked off the court, headed toward the locker room and laid down, draping a towel over her face. Outhit in Arthur Ashe Stadium by another big hitter, Danielle Collins, two-time US Open champion Osaka was left to contemplate a second consecutive first-round loss at a Grand Slam tournament.
Collins reached her first major final at the Australian Open in January and displayed that same sort of hard-court talent with a 7-6 (5), 6-3 victory over Osaka in a shotmaking showdown that ended after Tuesday turned to Wednesday at Flushing Meadows.
"I'm the type of person that thinks a lot, to the point where I overthink. Sometimes when I play matches, I have to tell myself to stop thinking, just go more on instinct," said Osaka, who has been bothered by a bad back lately. "I feel like I just have to chill a little bit, because there's a lot of like random chaos in my head right now."
Last season, Osaka took two extended mental health breaks, including after her third-round exit in New York. This season, Osaka lost in the third round in Australia and the first round at the French Open, then sat out Wimbledon.
"Lately, I felt really restrained. I'm not really sure why," Osaka said. "I'm beginning to feel like I can't hit the shots that I know I can, like especially on my forehand. I don't know if it's a matter of practicing more or something like that. I just don't have the same feeling."
She is now ranked 44th, which means she could have been drawn to face anyone in the first round.
This was the sort of matchup Osaka used to dominate on this surface -- and against this particular player. Osaka won the US Open in 2018 and 2020 and the Australian Open in 2019 and 2021 and she entered the night 3-0 against Collins, taking every set they had contested with each other.
But Collins, a Floridian seeded 19th at the US Open, took time off the tour starting in July for a training block after being hampered by a bad neck, and that work clearly paid off.
"Felt like her plan was to immediately put me in defense, so she would have hit the ball no matter what type of ball I hit on her side of the court. I thought she did that pretty well," Osaka said. "I think that's kind of what she's known for -- to be extremely aggressive."
Earlier Tuesday, the top seed in the women's draw, Iga Swiatek, powered into the second round with a 6-3, 6-0 victory over Jasmine Paolini.
Swiatek is trying to become the first player since Serena Williams in 2014 to win seven titles in a year. She is 5-4 since her 37-match winning streak ended earlier this year, but the two-time French Open champion got sharper as the match went on Tuesday while supported by a number of Polish fans wearing red inside Louis Armstrong Stadium.
Swiatek said she was excited to see a photo of herself pictured on an advertisement in Times Square.
"Just trying to enjoy that, because I remember times where it was pretty hard for anybody to see me or hear me,'' Swiatek said. "Yeah, it just shows how much progress I have done on court, but also off court that I am in such a spot.''
No. 8-seeded American Jessica Pegula also raced through her opening match like Swiatek, needing just more than an hour before beating Viktorija Golubic 6-2, 6-2.
"She's still No. 1 in the world and still going to compete really well and going to be tough to beat no matter what,'' Pegula said of Swiatek.
Swiatek may be toughest to beat on the red clay of Roland Garros, but she's already shown she can handle the hard courts, winning titles at Indian Wells and Miami earlier this year.
Emma Raducanu's defense of her surprising 2021 US Open championship ended with a 6-3, 6-3 loss to unseeded Alize Cornet in the first round Tuesday night. Raducanu, who was seeded 11th, is only the third woman to lose her opening match in New York a year after winning the title. The others were 2004 champion Svetlana Kuznetsova and 2016 champion Angelique Kerber.
Advancing in straight sets on Tuesday were No. 6 seed Aryna Sabalenka, No. 9 Garbine Muguruza and No. 21 Petra Kvitova.
No. 4 Paula Badosa got off to a rough start, but won a second-set tiebreaker en route to a three-set victory over Lesia Tsurenko. No. 22 seed Karolina Pliskova, the runner-up here in 2016, outlasted Magda Linette in a third-set tiebreaker 6-2, 4-6, 7-6 (10-8), while No. 13 Belinda Bencic also advanced over Andrea Petkovic, who is headed into retirement.
Petkovic, a little more than a week before her 35th birthday, shared a hug with her opponent and soaked up a warm ovation from the fans.
The German won seven singles titles and reached as high as No. 9 in the rankings. She made her decision recently and teared up as she explained it afterward.
Petkovic said she still loves the game but "it's more the body that is not allowing me to play tennis anymore in a way that I want to play it, train the way I want to train, just play a full season really.''
American Sloane Stephens dropped the first set against Greet Minnen but rallied for a 1-6, 6-3, 6-3 win.
Wimbledon champion Elena Rybakina tumbled in the first round, losing 6-4, 6-4 to Clara Burel of France, who came through qualifying to earn a spot in the main draw.
Rybakina was seeded only 25th, with her victory in the most recent Grand Slam not boosting her in the rankings because no points were awarded at the tournament this year. Rybakina, who was born in Russia but represents Kazakhstan, said before this tournament she thought that was unfair, adding she didn't even feel like a Wimbledon champion.
Jelena Ostapenko, the No. 16 seed, fell to Qinwen Zheng 6-3, 3-6, 6-4.
Sofia Kenin, the 2020 Australian Open champion, was knocked out in straight sets by Wimbledon quarterfinalist Jule Niemeier, who came away with a 7-6 (3), 6-4 victory.
American Amanda Anisimova, the No. 24 seed, lost to unseeded Yulia Putintseva 3-6, 3-6. Afterward, Anisimova posted to Instagram that she had broken her toe at last week's US Open tuneup tournament in Cincinnati and was still receiving injections in her foot as she recovers.
Up next on Wednesday, Serena Williams will be back under the US Open lights in Arthur Ashe Stadium.
Williams will play the leadoff match of the night session in the main stadium, facing No. 2 seed Anett Kontaveit of Estonia. They will be followed by defending men's champion Daniil Medvedev against Arthur Rinderknech of France.
Williams beat Danka Kovinic on Monday night to begin what could be the final tournament of her career. That helped draw the largest crowd ever for a US Open night session, which had more than 29,000 fans.
The Associated Press contributed to this report.