By Martyn Herman

LONDON Nov 22 (Reuters) - Novak Djokovic put the finishing touch to a magificent season by beating Roger Federer 6-3 6-4 to win the ATP World Tour Finals on Sunday for the fifth time in his career.

The Serbian underlined his complete dominance of men's tennis with another immaculate display to become the first player in the year-ending tournament's 46-year history to triumph four times in a row.

Federer brought the tournament to a close in anti-climactic fashion with a double-fault although not as much as a year ago when he pulled out of the final with back injury.

After a modest celebration Djokovic walked back to his chair and wrote "And now for vacation" in Serbian on a camera lens.

How he deserves one.

The 28-year-old has stomped through the season to leave his rivals trailing in his wake -- securing the year-end world number one ranking weeks before the London finale.

He won three of the year's four grand slams beating the evergreen Federer in the Wimbledon and U.S. Open finals to take his career haul to 10 and would have celebrated the rarest of 'calendar year slams' had it not been for an inspired Stanislas Wawrinka in the French Open final.

Not only that but he won six of the year's Masters Series crowns and ended the year with an 82-6 win loss record -- half of those defeats coming against Federer including in the group stages earlier in the week at the O2 Arena.

Since losing to Ivo Karlovic in the quarter-finals in Doha at the start of the year Djokovic has reached the final of all 15 tournaments he entered.

Federer whose record 17 grand slams could come under threat from Djokovic did beat the Serb 7-5 6-2 on Tuesday to end his 23-match winning run and also inflict on him a first indoor loss for three years.

With the stakes raised though the 34-year-old made far too many errors on Sunday while Djokovic's defences proved largely impenetrable but for the odd flash of Swiss magic that had his large red and white fan club chanting their approval.

"I returned more balls back than I did five days ago" Djokovic told a news conference.

"Obviously sitting here with this trophy alongside me I couldn't ask for a better finish of the season.

"This season definitely stands out. I can't say I expected it not at all. But I always gave my best and I'm always asking from myself the most."

Federer's chances were fleeting.

He had the first break point in the second game but fluffed a forehand into the net.

In the next game a near-identical forehand found the net to give Djokovic the break and from there he never looked back.

The clinical Djokovic teased Federer into a volley error on set point in the ninth game to move ahead.

Federer bidding for a record-extending seventh title at the year-ender was staring at the abyss when he trailed 3-4 0-40 in the second set but escaped with five straight points.

Djokovic was unrelenting though and wore the 34-year-old Federer down with one brutal rally two games later clinching victory on his second match point when Federer's second serve sailed long.

Djokovic has now levelled his head-to-head record with Federer for the first time in his career at 22-22.

The previous day he also caught up with Rafael Nadal beating the Spaniard to even their series at 23-23.

AFP