Defending champion Novak Djokovic has been handed an early showdown with Roger Federer as the world No.1 launches his bid for a fourth successive ATP Tour Finals title.

Djokovic arrives in south London hoping to win the prestigious season-ending event for a fifth time to cap another remarkable year that saw him win three grand slam crowns and cement his position on top of the world rankings.

The 28-year-old Serb will get a quick test of his appetite for further success on the banks of the River Thames when he faces Swiss great Federer in the 43rd instalment of their rivalry.

They are tied at 21 wins each, with Djokovic defeating Federer in the Wimbledon and US Open finals this year.

Federer is no slouch at the Tour Finals either, having won the tournament a record six times, but not even he reeled off four successive titles and Djokovic would become the first player to achieve that impressive feat if he lifts the trophy on November 22.

If Djokovic triumphs he will also draw level with Pete Sampras and Ivan Lendl as five-time Tour Finals winners.

Also in Djokovic’s group are Japan’s Kei Nishikori, his first opponent when the event gets underway on Sunday, and Czech world No.5 Tomas Berdych.

“This has been, by far, the most successful season of my life and I just try to better it,” Djokovic said.

Despite having won so much over the past 11 months, 10-time grand slam champion Djokovic has shown no signs of easing up as the season winds down.

Since losing to Federer in the Cincinnati final in August, Djokovic has embarked on a 22-match winning run that has brought him the US Open, the China Open and Masters 1000 titles in Shanghai and Paris.

The other group in the round-robin tournament, which features the world’s top eight players, sees Rafael Nadal, Andy Murray, Stan Wawrinka and David Ferrer pitted together.

Most of the interest in that group will focus on former Wimbledon champion Murray.

The world No.2 has never won the Tour Finals, but he may not be too concerned if he makes an early exit on home turf this year as he has made the Davis Cup a priority in recent months.

Murray has led Great Britain in their first Davis Cup final in 37 years and his country will bid for a first title since 1936 when they face Belgium in Ghent less than a week after the end of the Tour Finals.