Don't make Roger Federer angry. You won't like Roger Federer when he's angry. Neither will the guy unlucky enough to be playing against him at the time.
That's apparently what the crowd at Roland Garros did during Federer's quarterfinals match against Juan Martin del Potro of Argentina. The 16-time grand slam champion had just hit one into the net to go down two points in the second set tie break when he vented some frustration on the fans, who made more noise than he would have liked during the rally.
The television replay showed that Federer screamed, "Shut up!" to the crowd.
"That's about as angry as you've ever seen Federer," John McEnroe said.
Fed eventually dropped the second set to go down 6-3, 7-5. But perhaps the outburst stirred something inside Federer that presumably no opponent is going to want to face. He dominated from that point on, winning the next three sets while losing just five games total en route to another victory to reach his record-tying 31st Grand Slam semifinal.
[H/T to Busted Racquet]