Novak Djokovic has overcome a fierce challenge from Juan Martin del Potro to defend his Shanghai Masters title with a 6-1, 3-6, 7-6 (7/3) victory, improving his phenomenal winning streak in China to 20 matches.

The Serbian top seed looked set to wrap up the final in double-quick time after a one-sided first set – but the Argentine, who conquered Rafael Nadal in the semi-finals, hit back hard to take the match into a third set tie-break.

Djokovic held his nerve in the shoot-out to win a gripping contest lasting more than two-and-a-half hours for his fifth title of the season.

The victory keeps alive his slim chances of overtaking Nadal in the battle for the year-end number one ranking.

“It was a great experience again in Shanghai with a thrilling performance from both my opponent tonight and myself,” said Djokovic, who struck 47 winners in total and was particularly impressive at the net, winning 18 of 19 points.

“I think the tournament had a fantastic final. I’m just very glad to go out as a winner from the court tonight from such a close match.”

“I think either one of us could really take the title. I just managed to hold my emotions and I managed to believe in the victory enough in the end to play the right shots at the right time,” added the Serb, who also won last week’s China Open in Beijing.

Del Potro came into the final against the top seed brimming with confidence after his semi-final demolition of Nadal, but was immediately on the back foot in breezy conditions at the Qizhong Tennis Centre.

The 26-year-old Serb established an iron grip on the first set with a double break, dictating the play and not allowing the sixth seed to produce the thundering groundstrokes that dispatched Nadal.