World number one Iga Swiatek and sixth seed Coco Gauff underlined their credentials as US Open favourites by comfortably reaching the third round.
Defending champion Swiatek of Poland defeated Australian Daria Saville 6-3 6-4 in New York.
And 19-year-old American Gauff also won in straight sets, beating Russian teenager Mirra Andreeva 6-3 6-2.
The wins keep Swiatek and Gauff on course to potentially meet in the quarter-finals.
Meanwhile, two-time Grand Slam winner and 18th seed Victoria Azarenka was stunned by China's Lin Zhu, who won 6-3 6-3 to go through to the third round.
World number 44 Zhu will next play Swiss 15th seed Belinda Bencic, who defeated British qualifier Lily Miyazaki 6-3 6-3.
Swiatek is looking to become the first woman to defend her US Open title since American Serena Williams won a hat-trick of titles from 2012.
She will next play Slovenia's Kaja Juvan on Friday for a place in the last 16.
"It wasn't easy but I'm happy I tried to play my game and play aggressively with a lot of intensity and I'm just happy to be in the third round," Swiatek said.
Gauff, looking for her first major singles title, had to fight back to see off German qualifier Laura Siegemund in the first round, but produced an impressive display in her second-round match to progress.
Andreeva, 16, has enjoyed an incredible rise in recent months, climbing from 293 in the world in December to 62nd and also reached the last 16 of the Australian Open and Wimbledon.
She displayed some excellent tennis of her own on Wednesday but found Gauff in inspired form.
"I just learned to be aggressive, because if you give her something she is going to take advantage," said Gauff, who needed three sets to beat the Russian in the French Open third round in June.
"She has a great future in front of her - I think she is going to be back on this stage many more times."
Gauff will next play Belgium's Elise Mertens for a place in the last 16.
Mertens, the 32nd seed, overcame 2022 Australian Open runner-up Danielle Collins of the United States 3-6 7-6 (9-7) 6-1.
Gauff and Collins' compatriot Taylor Townsend upset 19th seed Beatriz Haddad Maia of Brazil 7-6 (7-1) 7-5.
Townsend will next face Czech 10th seed Karolina Muchova, who beat Poland's Magdalena Frech 6-3 6-3.
Kazakhstan's fourth seed Elena Rybakina advanced to the third round via a walkover after Australia's Ajla Tomljanovic withdrew with an injury.
Source: BBC
BDST: 0955 HRS, AUG 31, 2023
SMS