John Isner, ace machine watch 2013 Isner seemed to pick up a slight niggle at the Hopman Cup but thankfully he seems to be on course for the Australian Open! This is a player that at 6ft 9 has a sporting idol who was in the NBA and not tennis but has ferocious power off the serve and forehand! The proof is in the pudding that on his day he is the most devastating player in the world! Last year he took the racket out of Federer's hand to beat him in Switzerland in the Davis Cup before beating Djokovic in Indian Wells! Isner also has the record for the most aces in a match (113). The ferocious power plus enormous serve from such a height mean that if John gets it all together he is going to be unstoppable come the Australian Open which gets underway on January 14th in Melbourne.