Intro:

Defending champion Novak Djokovic beat Juan Martin Del Potro over three sets to reach the semi-finals of the ATP World Tour finals on Thursday.

Script:

Novak Djokovic took on Juan Martin Del Potro at the ATP World Tour Finals on Thursday in the second Group B match of the day - with both men knowing that a straight sets win would see them reach the semi-finals with a match to spare.

After a shaky opening game world number two Djokovic cruised through the first set 6-3.

A tight start to the second set unfolded, with Del Potro eventually making the break through to lead 3-2.

Despite enduring some sustained pressure on serve, the Argentine held firm to take the second set 6-3 and level the match.

He also enjoyed the first chances of the third set, squandering a break point chance at 1-1.

Djokovic then broke at 3-2 and never let Del Potro back in with a chance.

He produced a clinical final service game to take a 6-3, 3-6, 6-3 win.

His bid for a third consecutive London title remains on course as the win saw him book a place alongside Rafael Nadal in the final four.