Roger Federer proved that age is only a number once again, as he produced a vintage performance against Novak Djokovic. The 38-year-old's 6-4, 6-3, victory also ensures Rafael Nadal ends 2019 as world number one.
Roger Federer produced a wonderous display of power, grace and precision to sweep Novak Djokovic aside and reach the final four in London, ending the Serb's bid to end the year as the world number one.
In the 49th meeting between the two great rivals, Federer halted a five-match losing run against Djokovic and gained a little consolation for his Wimbledon final defeat earlier this year.
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 a majority of the 17,000 fans in the arena, Federer's array of shots simply left Djokovic with no answer, as the Serb's defeat means Rafael Nadal will end the year as world number one for the fifth time.
Djokovic served two double faults in the third game of the match and Federer pounced to break.
With Federer dropping only three points on serve in the opening set and serving eight aces, Djokovic was not given a sniff of an opportunity.
Federer faced only one break point in the match, in the fourth game of the second set, and saved it with a volley after battering a forehand deep into the corner.
He broke in the next game to lead 3-2 and again in the final game to win to deafening roars.