The Red Devils stopper played alongside the Arsenal marksman during their youth days, and says his drive and determination have not changed as he has matured.
Silvestre believes Henry has improved every year and is one of the best strikers on the globe, alongside the likes of Ruud van Nistelrooy, Ronaldo and Raul.
"Thierry has always worked hard. At 15 he was already a long way ahead of us," said Silvestre to L'Equipe. "He never turned his attention from the match he has to play.
"As long as I can remember, he has always improved, season after season, and today he has joined the greatest strikers, Ronaldo, Raul and van Nistelrooy.
"Along with technique, his running is incredible. It is impossible to remain in touch with him if he decides to leave you."
