World number one Iga Swiatek came out on top in a meeting of Grand Slam champions as she beat Sloane Stephens to reach the US Open third round.

Swiatek will next face American Lauren Davis who beat 28th seed Ekaterina Alexandrova 0-6 6-4 7-6 (10-5).

Eighth seed Jessica Pegula and three-time finalist Victoria Azarenka also advanced on day four in New York.

Azarenka beat Ukraine's Marta Kostyuk 6-2 6-3 and will face Croatia's Petra Martic next, after the world number 54 knocked out Spanish fourth seed Paula Badosa.

Martic came through 6-7 (5-7) 6-1 6-2.

Swiatek has won 52 matches this year, including a 37-match winning streak that included her French Open title win.

However, she has not gone beyond the quarter-final stage of a tournament since losing in the third round at Wimbledon in July.

Her best result at Flushing Meadows is a fourth-round showing in 2021.

American Pegula, who has reached the Australian Open and French Open quarter-finals this year, beat Aliaksandra Sasnovich of Belarus 6-4 6-4.

Meanwhile, Czech 21st seed Petra Kvitova advanced after her Ukrainian opponent Anhelina Kalinina withdrew with illness, while Switzerland's Olympic champion Belinda Bencic beat Romania's Sorena Cirstea 3-6 7-5 6-2.

France's Alize Cornet, who ended Emma Raducanu's reign as US Open champion in the first round, needed treatment before the final set because of the effects of the heat but recovered to beat Czech Katerina Siniakova 6-1 1-6 6-3.

There was a much quicker win for two-time Grand Slam champion Garbine Muguruza, as the Spaniard beat another Czech, Linda Fruhvirtova, 6-0 6-4.