Konta, the ninth seed, was defeated in three sets by Romania's Sorana Cirstea in the pair's first meeting since an acrimonious Fed Cup rubber from 2017, which led to Romania captain Ilie Nastase being removed from the grounds.

Nastase abused Konta and British captain Anne Keothavong and swore at the umpire.

Konta left the court in tears with the umpire halting the match for 25 minutes.

After the match Cirstea told British media she believed that Konta had "overreacted" to the situation and needed to "toughen up."

Today's meeting was a controversy-free affair, with Konta taking the first set 6-2 before Cirstea recovered from being a break down to take the second set on a tiebreak 7-6.

Cirstea then won the deciding set 6-4 to take victory in two hours and 50 minutes.

Tenth seed Muguruza was the day's other high-profile casualty on the women's side as she lost 7-5, 6-3 to Bulgaria's Tsvetana Pironkova.

After the exit of top seed Karolína Plíšková yesterday, Sofia Kenin was the highest women's seed left in the draw, and the American progressed comfortably in the first match of the day on the Arthur Ashe Stadium court as she won 6-4, 6-3 against Canada's Leylah Fernandez.

On the men's side it was an easier day for the top-10 seeds in action.

After benefiting from a retirement in round one, Austria's Dominic Thiem, seeded second, won 6-3, 6-3, 6-2 against Indian Sumit Nagal.

Elsewhere, sixth seed Matteo Berrettini of Italy won in three close sets against France's Ugo Humbert 6-4, 6-4, 7-6, while eighth seed Roberto Bautista Agut of Spain won 6-3, 3-6, 6-3, 6-4 against Serbia's Miomir Kecmanović.