Roger Federer getting beat after leading 2 sets to 0?

Wow, what a shocker. What happened to Federer? He never changed gears like he always does one goes down 2 sets to 0. Looked like he completely choked, don't get me wrong I was very happy for Tsonga but Tsonga has never beat Federer in a Grand Slam before especially being 2 sets down. Sucks that he has to play Djovokic but Djovokic or Nadal most likely will play better then Federer and destroy him. I just couldn't believe my eyes when Federer had no break points on Tsonga's serve after that one break of serve in the first set. Usually he goes to the next gear then mix things up and make big hitters like Tsonga over hit. Ever the point where Tsonga fell got back up and hit a return to eventually win that point was amazing. More and more people are starting to beat Federer. Is he in trouble now that he is older and have younger guys playing well? Will he win another grand slam? Will he have to change his game like Agassi did to win 3 more grand slams? What are your thoughts?