Juan Del Potro is enjoying tennis again after nearly retiring

Starting with the 2005 French Open and running through the 2013 U.S. Open, Del Potro was the only man to win a Grand Slam event other than the "Big Four" of Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray. There was every reason to believe the 6-foot-6 Argentine player would expand that group to five.