Mourinho’s former team humiliated United 4-0 in the first leg at Stamford Bridge and the Red Devils go into the weekend’s encounter 18 points behind the Blues.
The Portuguese has however raised up the issue of his side’s tight fixture schedule, pointing to the fact that Chelsea are not playing in Europe as an advantage.
“First of all, some guys are fresh, some guys are tired,” he said. “That’s very important in football.
“But, for some reason, they are top of the league. It’s not just because they are fresh.
“It’s also because they have individual quality and they have collective quality.
“They have a certain style of play, they stick to it, they do it very well.
“Not every team defends with 11 players, and they defend with 11 players.
“Not every team is so objective in their counter attacks.
“They are very objective in the counter-attack and they have individual players out of the context of the game that can also resolve the problems.
“So they are a very strong team.”