World number one Novak Djokovic booked his place in the semi-finals of the Cincinnati Open with a three-set win over Gael Monfils.

The Serb eventually overcame the French number eight seed 3-6 6-4 6-3 to extend his record for the 2011 season to 56 wins and one defeat.

The Frenchman broke Djokovic's serve in the opening game of the match and went on to seal the first set, although Djokovic hit back to secure the second set.

Djokovic ensured there was to be no upset by breaking the Monfils serve in the first game of the third set and he saw out the rest of the match in Ohio.

The number one seed will face Tomas Berdych, who beat Roger Federer in the last eight, in the semi-final on Saturday.

Andy Murray will play Mardy Fish in the other last-four match.