Carlo Ancelotti claims age is no barrier to success, saying Paolo Maldini was 39 years old when he collected a Champions League winners' medal with AC Milan in 2007.
The Paris St Germain coach last week signed David Beckham for the remainder of the season, with the Englishman turning 38 in May this year.
Ancelotti told French TV programme beIN Sport: "It's true that he's 37 but he's still a player.
"I remember a certain player won the Champions League at 39 and his name is Maldini.
"Beckham still has the motivation and the physical condition and he's not had many injuries in his career.
"He's one of the most serious and professional players I've ever known."
Beckham will join up with PSG on February 11, after the international break.
He has signed a five-month contract but will consider extending it on a rolling basis if the Qatar-owned club are interested in doing so ahead of next season.
High-spending PSG are still in the Champions League and will face Spanish club Valencia in the last 16 next week.