Zlatan Ibrahimovic has been warned against making an early comeback for Manchester United by surgeon Dr Freddie Fu, who operated on his knee in May.
Ibrahimovic has not played since damaging knee ligaments in United's Europa League quarterfinal against Anderlecht in April, but after signing a new one-year deal in the summer, has hinted he could return soon.
United boss Jose Mourinho has been more cautious and suggested the 35-year-old will not be ready until January, despite including him in the squad for the Champions League group stage which runs from September to December.
"I have no worry about his injury as it always takes time to fully recover," Dr Fu, chairman of the Department of Orthopaedic Surgery at the University of Pittsburgh School of Medicine, told the South China Morning Post.
"In fact the EPL has just started and I am sure Manchester United would not need the player urgently for any crucial game either in the league or European competitions.
"He is very strong but soccer is still a combative sport.
"As a doctor, of course I want to see him return as slow as possible, only when he is fully fit for the game. There have been many cases of a player returning prematurely with bad consequences."
Ibrahimovic, who scored 28 goals in 46 games for United last season, will turn 36 on Tuesday.
But despite coming towards the end of a career that has already spanned more than 800 games over 18 years for eight clubs in six different countries, Dr Fu expects United's new No. 10 to make a full recovery, in part because he has the knees "of a 15-year-old boy."
"I have treated almost 60 professional players and Ibrahimovic is certainly one of the best and strongest players I have ever operated on," he added.
"He has a very strong attitude. Even before the operation, he firmly believed he would come back in his soccer career and would not retire just because of the injury.
"When we examined his knee, other than the ligament injuries he sustained, the joint, the muscles and other parts of his knee are all in top-notch condition, just like those of a 15-year-old boy and not a soccer player who has been in fierce physical competition for so many years.
"His operation went very smoothly."