BARCELONA, Spain -- Rafael Nadal's doctor says the 14-time Grand Slam winner will receive stem cell treatment on his ailing back.

Angel Ruiz-Cotorro told The Associated Press by phone on Monday that "we are going to put cells in a joint in his spine" next week in Barcelona.

The Spanish tennis star was already sidelined for the rest of the season after having his appendix removed last week.

Ruiz-Cotorro, who has worked as a doctor for Nadal for the past 14 years, said Nadal's back pain is "typical of tennis" players and that the treatment is similar to stem cell treatment Nadal received on his knee last year.

He said Nadal is expected to return to training in early December.