“To be up there with both men and women is something that’s super-rare, and it actually feels good,” said Williams, who said she was “really excited” to reach 307.

“Obviously I want to keep that number going higher,” added Williams, who will get her chance when she takes on Kazakhstan’s Yaroslava Shvedova for a quarter-final berth.

In the one hour it took to subdue Larsson, Williams appeared untroubled by the shoulder injury that has slowed her since her Wimbledon triumph.

“It definitely feels solid,” she said. “I’m doing a lot of work on it so I can keep it in this position.”

While Williams encountered little resistance as she moved a step closer to an Open Era record of 23 grand slam titles – and Margaret Court’s all-time record of 24 – it was another story for the top men’s seeds in action.

Wawrinka, a two-time grand slam winner and twice a semi-finalist in New York, had the closest call, saving a match point in a 4-6, 6-3, 6-7 (6-8), 7-6 (10-8), 6-2 victory over Britain’s Dan Evans.

The 31-year-old third seed saved the match point at 5-6 in the fourth set tiebreaker, breaking the will of his 64th-ranked opponent.

“I was lucky to get through, saving match point,” said Wawrinka after reaching the last 16 in Flushing Meadows for a fifth straight year.

Wawrinka next faces either Australian Nick Kyrgios or Ukrainian Illya Marchenko, who closed out the night’s action on Arthur Ashe stadium.

Nishikori, who has dropped a set in each of his matches so far, next faces either big-serving Croatian Ivo Karlovic or US qualifier Jared Donaldson.

Juan Martin del Potro, whose career was nearly derailed by injuries after his 2009 US Open triumph, fired 37 winners in a 7-6 (7-3), 6-2, 6-3 victory over Spanish 11th seed David Ferrer.

He next faces eighth-seeded Austrian Dominic Thiem, who celebrated his 23rd birthday with a 1-6, 6-4, 6-4, 7-5 victory over Pablo Carreno Busta of Spain.

Women’s fourth seed Agnieszka Radwanska advanced with ease, dispatching France’s Caroline Garcia 6-2, 6-3 to set up a meeting with Croatian Ana Konjuh, a 6-3, 3-6, 6-2 winner over American Varvara Lepchenko.

Hungarian Timea Babos put a scare into Romanian fifth seed Simona Halep, surging back in the second set and taking a 3-1 lead in the third before falling 6-1, 2-6, 6-4.

Halep, who fell in the semi-finals to eventual champion Flavia Pennetta last year, will play Spain’s Carla Suarez Navarro for place in the quarter-finals.

Suarez, also celebrating a birthday Saturday as she turned 28, defeated Russian Elena Vesnina 6-4, 6-3.

Sixth seed Venus Williams, whose seven Grand Slam titles include US Open crowns in 2000 and 2001, coasted into the round of 16 with a 6-1, 6-2 win over German Laura Siegemund, setting up a meeting with 10th-seeded Karolina Pliskova, a 6-2, 6-4 winner over Anastasia Pavlyuchenkova.