The pair traded barbs when they both worked in Italy.
So when Inter knocked Chelsea out of the Champions League, it was perceived as a personal victory for Mourinho; and when Ancelotti achieved the Double, something Mourinho never did at Chelsea, it seemed to be a counter-strike in this battle of egos.
But a truce came prior to the Champions League clash with Inter, in the tunnel at the San Siro.
"I approached him," says Ancelotti.
"Our relationship is good and I want to maintain this because he is one of the best coaches in the world."