The US Open lost one of its most bankable and marketable stars on Sunday when Maria Sharapova announced an 11th hour withdrawal from the tournament on account of a leg injury that has dogged her for the past couple of months.

The U.S. Tennis Association made the announcement in a statement.

Sharapova had been the highest-seeded rival in Williams’ half of the US Open draw, a status that now belongs to seventh-seeded Serbian Ana Ivanovic, a possible semi-final foe for Williams. “I executed pretty well so hopefully I’m going to do it again”, Gavrilova said on Saturday.

The U.S. Open will run until September 13, with Serena Williams looking for a calendar Grand Slam on the women’s side. I have a very strong personality and I think you notice it when I play.

The world No. 3 has not played a match since Serena Williams beat her 6-2, 6-4 in the Wimbledon semi-final, and yesterday she used her Facebook page to confirm her decision.

“I will try limit my expectations but it’s not easy”. “I’m feeling better, just a time thing”, she said.

“Has she got a great chance?”

Renowned for her focus on court – look out for the pre-serve routine at the back of the court – Sharapova is arguably the toughest player mentally on the WTA tour so her opponents know they will have to see out a match rather than wait for her to lose it.