Justin Bieber is damn serious about his stroke, so serious ... he's seeking professional help.
Justin was taking tennis lessons this weekend in L.A., concentrating on his forehand. We've already seen Sporty Biebs kill it in hockey, skateboarding, ping pong and hoops. Remember, he already has an MVP trophy from an NBA Celebrity All-Star game.
Anyway, tennis is a way better pastime than pissing off Mayan Gods by pulling down your pants -- so kudos to Bieber.