The US Open semi-finalist entered the WTA Tour event with the intention of gaining match practice on clay before the upcoming French Open.

That delayed grand slam takes place from 27 September to 11 October in Paris, switched from its original May start because of the COVID-19 crisis.

Williams fell short in her bid to land a record-equalling 24th grand slam when she was edged out by Victoria Azarenka in New York this week, when she needed medical assistance for the Achilles pain.

She stressed afterwards that she intended to play the French Open, but the Rome event, which begins on Monday, has now been scratched from her plans.

Former world No.1 Williams said in a statement released by the WTA: "I regretfully must withdraw from the Internazionali BNL d'Italia due to an Achilles strain."

Petra Kvitova and Bianca Andreescu will also be absent from the tournament after the WTA announced their withdrawals.

Simona Halep is among those returning to action, however, with the world No.2 having opted to miss the US Open because of concerns related to the pandemic.