Novak Djokovic survived a scare before easing through to the semis, but Rafael Nadal and Roger Federer’s US Open preparations have hit a snag.

Novak Djokovic barely broke a sweat as he routed Ryan Harrison, while Andy Murray defeated David Nalbandian and Rafael Nadal beat Julien Benneteau.

Signs of tiredness betrayed Serena Williams as she continued her return to form with a 6-3 7-6 victory over Lucie Hradecka at the Cincinnati Open.

Roger Federer has cast aside bad memories of his US Open defeat to Argentina’s Juan Martin Del Potro by beating him 6-3 7-5 at the Cincinnati Open.

An angry Andy Roddick lost his cool as he crashed out of the Cincinnati Open in the first round after a three-set defeat to Philipp Kohlschreiber.