LONDON — Roger Federer stopped Novak Djokovic's ATP Finals winning streak at 15, beating the top-seeded Serb 7-5, 6-2 to reach the semifinals at the season-ending tournament on Tuesday.
Djokovic, who has already clinched the year-end No. 1 ranking, had not lost at the ATP Finals since 2011, winning the last three elite titles for the top eight players in the world.
But Federer was strong at the O2 Arena, as he usually is on an indoor hard court.
The six-time champion broke Djokovic in the final game of the first set, and again early in the second.