Roger Federer put a stop to Novak Djokovic's 43-match winning streak, hitting his 18th ace Friday for a 7-6 (5), 6-3, 3-6, 7-6 (5) victory at the French Open semifinals. Djokovic was undefeated since losing to Federer in late November. "It had to end somewhere,” said Djokovic, who is the only player to have beaten Federer more than eight times. “Best five months of my life, my tennis career. I cannot complain.” Federer will go for his 17th Grand Slam title Sunday as he faces off against five-time French Open champion Rafael Nadal, who defeated Andy Murray.