Juan Martin del Potro is hoping to turn tennis' Big Four into a quintet in 2013.
The big-hitting Argentine's season ended Sunday when he wasted a one-set lead against Novak Djokovic to lose 4-6, 6-3, 6-2 in the semifinals of the ATP finals. But his strong end to the year has made Del Potro confident he can once again challenge the sport's biggest names for Grand Slam titles next season - like when he won the 2009 U.S. Open before a serious wrist injury.
Del Potro says ''I'm getting closer every day'' to the likes of Djokovic, Roger Federer, Andy Murray and Rafael Nadal. He says ''maybe that could be my big challenge for next year, my big goal, trying to fight (for all the) Grand Slams with this group.''