It may or may not have been said with his tongue firmly in his cheek but Olympic sprint superstar Usain Bolt has called on Manchester United manager Sir Alex Ferguson to hand him a trial.Bolt cemented his position as the fastest man on the planet when defending his Olympic 100m title on Sunday. The Jamaican has been musing about his next move, with a step up to 400m a possibility.But he is not short of confidence and has often claimed he has the skill to make it as a footballer.He is a huge United fan, has met Ferguson and the players in the past, and has put out a call for a trial."People think I am joking, but if Alex Ferguson called me up and said, 'OK let's do this, come and have a trial', it would be impossible for me to say no," Bolt is quoted as saying in the Sun."I would not take up the challenge if I didn't think I was good enough. I am a very accomplished player and know I could make a difference."I would be the fastest player in the team - but I can play as well."He added: "I am in Britain for a few more days. If Alex Ferguson wants to give me a call he knows where I am."