Serena Williams has been forced to withdraw from her quarter-final clash against Petra Kvitova due to injury.
The world number one has complained of a thigh injury and also has no plans to compete in Rome next week.
The decision means that Kvitova will move straight into the semi-finals without hitting a ball.
Meanwhile, on the men's side, Rafael Nadal will take on Tomas Berdych today for a place in the final four.