The head of Spain's national organ transplant organisation on Friday suggested that French footballer Eric Abidal would have difficulty returning to the sport after a liver transplant.
The 32-year-old Barcelona defender is due to have a transplant in the coming weeks, his club said on Thursday, a year after he previously underwent surgery to remove a liver tumour.
Rafael Matesanz told the Marca newspaper, however, that he believed that it would be "very difficult" for him to play again.
"It's clear that everything will go well and that he could play sport at a high level but football is a contact sport and one of the things that you have to avoid after a transplant is trauma and blows in that area," he was quoted as saying.
Matesanz said Abidal was "a strong person, an elite sportsman and he will have a normal life. And it's clear that he will be able to play sport".
But he added: "He has to take a series of precautions for the rest of his life, including not getting hit in that area. He will have medical treatment for life and will have to have regular check-ups."
The internationally-renowned doctor added that rejection was not a problem in his opinion because of the player's level of fitness.
On Thursday, Jean-Daniel Chiche, head of the medical foundation Life-Priority Fund where Abidal is an ambassador, insisted that the player was "ready to fight and would play again" after his operation.
After Abidal underwent surgery in March 2011, he had not been expected to return to the pitch until August. But he made a surprise return on May 3 in the final minutes of Barca's return 1-1 Champions League semi-final tie with Real Madrid.
The defender has been a regular this season for the Catalan side, starting in 20 first division matches. But he has not played since picking up a hip injury playing for France in their friendly win over Germany, at the start of March.