Fourth seed Naomi Osaka overcame a scare to beat fellow Japanese player Misaki Doi in three sets and avoid a major shock in the US Open first round.
Osaka, who won the first of her two Grand Slams at Flushing Meadows in 2018, wobbled in the second set before recovering for a 6-2 5-7 6-2 victory.
Elsewhere, teenager Coco Gauff's hopes of another Grand Slam run were ended by 31st seed Anastasija Sevastova.
But top seed Karolina Pliskova and sixth seed Petra Kvitova advanced.
Osaka walked out on court wearing a face mask with the name of Breonna Taylor, a black woman who was shot dead by a policeman in the United States in March.
Asked about it in her on-court interview in front of the Bermuda banner, she said: "I have seven. It is quite sad seven masks aren't enough for the number of names - and hopefully, I'll get to the final and you will see all of them."
She later added in a news conference: "For me, I just want to spread awareness. I'm aware that tennis is watched all over the world but that maybe there is someone who doesn't know Breonna Taylor's story. Maybe they'll Google it after or something.
"I feel the more people know this story the more interested they will become in it."