ABU DHABI, United Arab Emirates - Novak Djokovic retained his title at the World Tennis Championship exhibition tournament in Abu Dhabi on Saturday by rallying past Nicolas Almagro of Spain 6-7 (4), 6-3, 6-4 in the final.

The top-ranked Serb swept past David Ferrer in straight sets to reach the final, but he got a tough test from the 11th-ranked Almagro.

"Absolutely enjoyed the final. It was a thrill again to be here and hopefully everyone who came here today enjoyed the final," Djokovic said. "I congratulate Nico. It is amazing; him coming here only a few days ago and having a late entrance to the tournament and performing this well yesterday and today."

Almagro, a late replacement at the tournament after Rafael Nadal pulled out because of a stomach bug, rallied from 3-1 down in the tiebreaker to take the first set.

Djokovic broke to lead 3-1 in the second set on his way to evening the match. The third set was much tighter, with both players holding serve after eight games until Djokovic went up 5-4 and then broke Almagro to clinch the victory.

Both players served 12 aces, but Almagro was only able to convert one of six breakpoint opportunities and won just 34 per cent of points when returning.

"I have had a lot of fun and I have to thank the organizers for calling me in the last minute because it is amazing to be here for me," Almagro said. "I congratulate Novak because he is the No. 1 player and the winner tonight."

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