Williams leads American charge at US Open

The ninth seed, on a renaissance path as she reached major finals this season for the first time since 2009, faces Czech Petra Kvitova, who knocked out pre-tournament favourite Garbine Muguruza in the previous round three months after coming back from a career-threatening injury.

Kvitova, seeded 13th, was stabbed in her left playing hand by an intruder at her home in December.

“What she’s gone through is unimaginable, unreasonable. The world we live in is just shocking,” said Williams.

“So for her, I think to be playing well is such a blessing. To be able to come out here and do what she needs to do, to clear her head, it’s such a beautiful thing to see. What else can I say except I‘m glad to see her back.”

American Sloane Stephens, back to her best after a year out because of a foot injury, faces Latvian 16th seed Anastasija Sevastova, who beat Maria Sharapova in the previous round.

She will be followed on Arthur Ashe Stadium by Williams, with Sam Querrey, the only American male player left in the draw, closing proceedings against big-serving Kevin Anderson.

Spanish 12th seed Pablo Carreno Busta against Argentine Diego Schwartzman will start action on the main arena.