Roger Federer lit up the O2 Arena with a dazzling 6-4 6-3 defeat of Novak Djokovic to hand the Serb an early ATP Finals exit and wreck his bid to end the year ranked number one.

In the 49th meeting between the two great rivals, Federer snapped a five-match losing run against Djokovic and gained some consolation for his heartbreaking Wimbledon final defeat.

After both men had been beaten by Dominic Thiem earlier in the group, their eagerly-anticipated duel was a straight shoot-out to join the Austrian in the semi-finals.

Roared on by the majority of the 17,000 fans in the arena, 38-year-old Federer produced an astonishing display of power, grace and precision and Djokovic simply had no answer.

Defeat for Djokovic means Rafael Nadal will end the year as world number one for the fifth time.

Federer dropped only three points on serve in the opening set, and only face one break point in the entire match which lasted just over one hour 13 minutes.

Earlier, Matteo Berrettini won his first match in London by beating Dominic Thiem 7-6 (7-3), 6-3.

The match was essentially meaningless as Austria’s Thiem had already qualified for the semi-finals after winning his first two round-robin matches while Berrettini had no chance of advancing after two losses.

Thiem didn’t play anywhere near as well as in his wins over Roger Federer and Novak Djokovic but came from a break down to force a tiebreaker in the first set.

However, Italian Berrettini raced out to a 6-1 lead in the tiebreaker and converted his third set point with an ace.

In the second set, the Italian broke for a 4-2 lead and served out the match to love, sealing the win with a forehand drop shot.