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.
Two-time French Open winner Swiatek saw off American Stephens, who won the 2017 US Open, 6-3 6-2.
Swiatek will next face American Lauren Davis who beat 28th seed Ekaterina Alexandrova 0-6 6-4 7-6 (10-5).
Sixth seed Aryna Sabalenka produced a remarkable comeback to beat Estonia’s Kaia Kanepi and advance.
The Belarusian, a semi-finalist at Flushing Meadows last year, came through 2-6 7-6 (10-8) 6-4 in a rollercoaster match.
However, fourth seed Paula Badosa became the latest top player to fall as she was beaten 6-7 (5-7) 6-1 6-2 by Croatia’s world number 54 Petra Martic.
Eighth seed Jessica Pegula and three-time finalist Victoria Azarenka also advanced on day four in New York.
Sabalenka has had a mixed season but managed to somehow overcome Kanepi, despite making 41 unforced errors and hitting 11 double faults.
Kanepi had led by a set and 5-1 after 56 minutes, was 5-2 up in the second set tie-break, and missed two match points on her serve, including one that was saved by a Sabalenka net cord.
Sabalenka went up an early break in the decider but, attempting to serve out the match at 5-4, hit three double faults, including one on match point, before producing an ace to save one of two break points.
She fell to the floor and laughed in disbelief as a long Kanepi forehand eventually handed her victory, with the two sharing warm words at the net.
Sabalenka will face France’s Clara Burel next.
Azarenka beat Ukraine’s Marta Kostyuk 6-2 6-3 and will now play Martic while American Pegula, who has reached the Australian Open and French Open quarter-finals this year, beat Aliaksandra Sasnovich of Belarus 6-4 6-4.
There was a quick win for two-time Grand Slam champion Garbine Muguruza, as the Spaniard beat Czech Linda Fruhvirtova 6-0 6-4. She now meets Czech 21st seed Petra Kvitova who had a walkover with her Ukrainian opponent, Anhelina Kalinina, withdrawing because of illness.
Switzerland’s Olympic champion Belinda Bencic beat Romania’s Sorana Cirstea 3-6 7-5 6-2 and will play former finalist Karolina Pliskova after the Czech defeated compatriot Marie Bouzkova 6-3 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.
She now plays American 19th seed Danielle Collins, a 6-2 7-5 winner against Spaniard Cristina Bucsa.