Coco Gauff passed a big test of her credentials for winning a second successive US Open after beating Elina Svitolina.

The 20-year-old American has set her sights on becoming the first woman to defend her Flushing Meadows title since Serena Williams in 2014 but her form coming into the tournament was not great.

She got through her first two rounds without excelling and was in trouble when 27th seed Svitolina took the opening set.

But Gauff showcased her fighting spirit to produce a 3-6 6-3 6-2 victory on Arthur Ashe.

“It means a lot, I knew today was going to be a tough match, every time I play Elena it’s hard,” Gauff said.

“I had to bring my best tennis, I thought I played well and I served a lot better than the other day.

“I tried to be more aggressive. She was playing well and aggressive, the difference was me being more aggressive after the first set.”

Olympic champion Zheng Qinwen enjoyed her first comfortable ride of the tournament.

The Chinese had to come from a set down in her opening two matches but she dropped just three games in a 6-2 6-1 victory over Jule Niemeier.

Paula Badosa, a Spaniard who was born in New York, is into the fourth round for the first time after a narrow 6-4 1-6 7-6 (8) win over Elena-Gabriela Ruse.