Roger Federer cruised into the fourth round of the US Open on Friday while Czech third seed Karolina Pliskova, chasing her first Grand Slam title, survived a scare.
Reigning French Open champion Ashleigh Barty, the Aussie second seed, also reached the last 16.
Williams continued her quest for a 24th career Grand Slam title to equal Margaret Court’s all-time record by crushing 44th-ranked Czech Karolina Muchova 6-3, 6-2 in 74 minutes.
“I had a lot of intensity today, which is really good for me,” Williams said.
The 37-year-old American, six times a US Open champion, has been a runner-up in three of the past five Slams, falling to Naomi Osaka in last year’s US Open final. She last won a Slam crown at the 2017 Australian Open while pregnant and hasn’t won the US Open title since 2014.
“I actually prefer playing in the day because I get to go home and actually see my baby,” Williams said.
Williams will face Petra Martic in the round of 16.
Pliskova, the 2016 US Open runner-up, outlasted Tunisia’s Ons Jabeur 6-1, 4-6, 6-4 while Barty dispatched Greek 30th seed Maria Sakkari 7-5, 6-3.
“Physically it was quite a tough battle,” Pliskova said. “It was important to win so it doesn’t matter how I feel. So pleased to be through.”
Barty and Pliskova are battling top-ranked defending champion Osaka to be world number one at the end of the Flushing Meadows fortnight.
Barty has the inside track because Osaka has so many points to defend. The Japanese 21-year-old must win the title to have any chance at staying on top while Pliskova must reach at least the semi-finals.
Pliskova, the 2016 US Open runner-up who could finish the fortnight as world number one, booked a spot in the last 16 against either British 16th seed Johanna Konta.
After taking the first set in 26 minutes, Pliskova broke to open the second. Jabeur, ranked 62nd, had her right knee retaped and battled back to break Pliskova three times in the second set, the last on a forehand winner to force a third set.
Pliskova broke to start the third set and seized another in the fifth game on an errant Jabeur forehand before advancing on a backhand winner after two hours and eight minutes.
“She improved the game a lot in the second set, she hit a couple unbelievable shots and got into her rhythm,” Pliskova said.
“Especially had to serve well. Was able to hit a couple aces in the third set which really helped. Physically it was quite a tough battle. It was important to win so it doesn’t matter how I feel. So pleased to be through.”
Johanna Konta (GBR x16) bt Zhang Shuai (CHN x33) 6-2, 6-3
Karolina Pliskova (CZE x3) bt Ons Jabeur (TUN) 6-1, 4-6, 6-4
Serena Williams (USA x8) bt Karolina Muchova (CZE) 6-3, 6-2
Petra Martic (CRO x22) bt Anastasija Sevastova (LAT x12) 6-4, 6-3
Ashleigh Barty (AUS x2) bt Maria Sakkari (GRE x30) 7-5, 6-3