Juan Martin del Potro has revealed that he is looking to compete for Grand Slam titles next year following his defeat to Novak Djokovic in the semi-finals of the ATP World Tour Finals.
The Argentine was beaten in three sets by the world number one on Sunday to end his hopes of winning the end-of-season event for the first time.
"They have been winning all the Grand Slams: Novak (Djokovic), (Roger) Federer, Rafa Nadal and now Andy Murray," said the 24-year-old.
"Maybe it could be my big challenge for next year, my big goal, trying to fight for all the Grand Slams with this group."
World number seven Del Potro ends the year with four singles titles to his name.
