The 35-year-old Monaco defender formerly of Porto, Chelsea and Real Madrid, says that his former coach's success can be explained by the fact he hates losing
The 35-year-old, who played under the Portuguese coach at Porto, Chelsea and Real Madrid, says the 50-year-old is a rare breed who will do anything to avoid the taste of defeat.
"When Mourinho loses he cannot deal with the defeats," Carvalho told the Daily Mail.
"He is simply not compatible with it. After a game has gone wrong and he loses, he is very difficult to work with the next day.
"To me what makes him so special is the detail he puts into his work.
"He wants every one of his players to evolve under him, but most of all he wants to win. We have won so many trophies together."
Since Carvalho worked under Mourinho at Porto in 2002, they have won two Primeira Liga titles, the Uefa Cup, Champions League, two Premier League titles and La Liga, among others.
Carvalho joined Monaco from Real Madrid earlier this summer on a free transfer.
He has represented Portugal 75 times, scoring on four occasions since his international debut in 2003.