Rafael Nadal might be forced to withdraw from the ATP World Tour Finals next week due to a shoulder injury.
Novak Djokovic, who is suffering from the same ailment, also might miss the event.
Nadal revealed that he hurt his shoulder in a training session, and is still hopeful that he will play in the prestigious year-end event.
However, some rumours are going around that he might skip it in order to be fully fit for the Davis Cup final against Argentina.
Do you know how to improve
your return to the first serve ?