Simona Halep has beaten Kateryna Bondarenko 6-3 6-4 to reach the third round of the US Open while Wimbledon finalist Garbine Muguruza’s poor run of form continued.

Halep, the second-seeded Romanian, posted her 34th hardcourt win of the season, and along with Serena Williams and Karolina Pliskova, is one of three players to post 40 main draw wins so far this season.

Ninth-seeded Spaniard Muguruza, who faced Serena Williams in the title match at the All England Club two months ago lost her third match of the four she has played since the biggest day of her career.

Muguruza, who has recently split with her coach, went down to British qualifier Johanna Konta of Britain who sprang a 7-6 (7-4) 6-7 (4-7) 6-2 surprise.

German 11th seed Angelique Kerber advanced over Italian Karin Knapp 7-5 6-2.

Sara Errani took revenge for Italy with her comeback defeat of Latvian Jelena Ostapenko 0-6 6-4 6-3.

German Andrea Petkovic beat Russian Elena Vesnina 6-3 7-6 (7-4) and former world No.1 Victoria Azarenka continued her comeback after 2014 injuries with a 7-5 6-4 defeat of Yanina Wickmayer.