Serena and Murray headline day four of US Open

NEW YORK - SEPTEMBER 01: Serena Williams of the United States serves the ball during her Women's Singles first round match against Kristie Ahn of the United States on Day Two of the 2020 US Open at the USTA Billie Jean King National Tennis Center on September 1, 2020 in the Queens borough of New York City. (photo: Al Bello/Getty Images/AFP)

Williams, the tournament's third seed, continues her bid for a record-equalling 24th singles Grand Slam against unseeded Russian Margarita Gasparyan.

The second-round match kicks off the evening session inside the main Arthur Ashe Stadium.

Murray will then take to the famous court to try to progress into round three at the expense of 15th seed Felix Auger-Aliassime of Canada.

The Scotsman came back from two sets down to win a thrilling five-set match first-round match against Japan's 49th-ranked Yoshihito Nishioka on Tuesday.

Murray is playing in the singles at a Grand Slam for the first time since a first-round exit at the Australian Open in 2019.

The 33-year-old is trying to rebuild his injury-ravaged career with a new metal hip that was installed last year.

Williams' chances of matching Margaret Court's record for the all-time number of Grand Slam singles titles were handed a boost on Wednesday when top seed Karolina Pliskova tumbled out of the tournament.

The Czech was stunned in straight sets by France's world number 50 Caroline Garcia.

The women's draw is missing a host of top players, either because of coronavirus fears or through injury, including top-ranked Ashleigh Barty and Simona Halep.

It has been more than three years since Williams won her 23rd Grand Slam title at the 2017 Australian Open -- when she was already pregnant with daughter Olympia.

The 38-year-old has come close since, reaching four major finals only to come away empty handed.

Also on court Thursday is second seed Sofia Kenin who plays Canada's Leylah Fernandez for a place in the third round.

In the men's draw second seed Dominic Thiem of Austria goes up against Sumit Nagal, who is the first Indian man since 2013 to reach the second round of a Grand Slam.

Third see Daniil Medvedev is also gunning for a spot in the third round Thursday, taking on Australia's 116th-ranked Christoper O'Connell.