LONDON (AP) ― Novak Djokovic remains the man to beat on indoor courts.

The defending champion made quick work of top-ranked Rafael Nadal 6-3, 6-4 to win the ATP World Tour Finals on Monday, extending his winning streak to 22 matches and claiming the elite season-ending title for the third time.

Djokovic, who has not lost a match since his defeat to Nadal in the U.S. Open final, returned superbly from the start to move his Spanish rival around the court and prevent him from dictating the points.

Nadal hit only nine winners and was broken three times.

Nadal and Djokovic have been dominant this season. Nadal replaced Djokovic for the No. 1 ranking last month, but the Serbian player proved again he still has the upper hand on hard courts by extending his head-to-head winning record to 13-7 on that surface.

Djokovic took an impressive start, hitting powerful groundstrokes to keep Nadal well behind his baseline while limiting his own mistakes.

Returning well, the Serb made the most of two of Nadal’s backhand errors to break in the second game. He had another chance in the fourth game after Nadal double-faulted, but a superb defensive play from the Serb ended with a shanked backhand.

Nadal got into the match from that point. He put Djokovic under pressure with his huge forehands in the next game and two unforced errors from the Serb allowed him to break back then even at 3-3.

But Nadal faltered in his next service game as he served a double fault at 30-30.

After a stunning exchange, Djokovic broke for a 5-3 edge following a series of volleys at the net. Standing in the middle of the court, the Serb opened his arms and screamed as the crowd erupted in cheers and greeted the players with a standing ovation.

Djokovic then benefited from a fortunate net cord and made sure he hit three good serves to seal the set on his first occasion with an ace.

Looking confident, Djokovic raised his game further in the second set, pinpointing his shots on the lines after breaking in the third game of the second set.

The Spaniard saved two match points and kept encouraging himself until the end, but a final forehand that was too long gave Djokovic the title.