Justin Bieber calls out Floyd Mayweather Jr over Twitter

Justin Bieber calls out Floyd Mayweather Jr over TwitterCanadian teen pop sensation and amateur Hilary Swank lookalike Justin Bieber has joined the ranks of boxing fans clamouring for a much-anticipated megafight between Manny Pacquiao & Floyd Mayweather Jr.Bieber tweeted his support in the early hours of Sunday morning after Manny Pacquiao's historic victory over Antonio Margarito in the