Federer Breaks Djokovic's Winning Streak

Roger Federer knows a thing or two about ending Novak Djokovic's winning streaks.

The Swiss brought an abrupt halt to Djokovic's astonishing 43-match winning run in the 2011 Roland Garros semifinals. He has now dealt the world No.1 his first defeat in 24 matches, producing a stunning 7-5, 6-2 victory to secure his place in the last four of the World Tour Finals.

In what has become arguably the greatest rivalry in the history of Open era men's tennis, Djokovic missed his golden chance to finally edge in front of Federer in their head-to-head after nine years of trying.

For those keeping score, Federer -- who received his usual raucous support in the O2 Arena -- now leads Djokovic 22-21.

The 43rd edition of this match-up did not disappoint, with Federer now assured of a place in the last four having stunned the three-time reigning champion here in two sets.

"It's always a thrill to come out here in the O2 Arena, also against a great player like Novak," said Federer on court. "With the year he's had, it's even more special. It was a special night for tennis. Cool atmosphere."