AC Milan club doctor Jean Pierre Meersseman believes loan signing David Beckham can continue playing for another five years at least, by which time the midfielder will be 38 years old.
"He will be at his top level in 15-20 days," he told Sky Italia. "The tests which he did showed that he is already very good.
"He has an exceptional physique which will allow him, as happened to (Paolo) Maldini or (Alessandro) Costacurta, to play for another five or six years."
The England midfielder is in Dubai with the rest of the Milan squad after joining the team on a short-term deal from the LA Galaxy and took part in his first training session with his new team-mates today.
Beckham has not played since the end of the MLS season in October, but captain Maldini is confident the former Manchester United star will be match fit again soon.
"Beckham is a great champion, but we shouldn't forget that he has come into a great team and a great club like Milan," said Maldini.
"We players don't care what his life is like off the pitch, we have found a lad who has not trained for two and a half months, but I have had the chance to talk to him and I noticed his determination and his great desire to put himself to work immediately to return to playing as soon as possible."
Beckham officially becomes a Milan player on January 7 and could make his debut four days later, against Roma at the Stadio Olimpico.
Milan coach Carlo Ancelotti has reiterated his belief that the former England captain will make a valuable contribution to the team before he returns to Los Angeles in March.
"This morning he took part in his first training session with the team," he said. "I believe he is an important player and that he will give his contribution to Milan.
"He is a player who can play in all three roles in midfield and he has immediately put himself at the disposal of the group.
"This week away will be useful to evaluate his physical condition and then we will evaluate when it will be possible to use him in official games."