Mourinho’s former club, who lead the Premier League by six points, have three games in 10 days over the festive programme.
United boss Mourinho accused the Premier League of favouring Chelsea with the fixture scheduling and deliberately making it harder for the chasing pack.
“The busy period is for some clubs, not for everyone,” said Mourinho.
“If you analyse clubs, the fixtures are chosen to give rest for some and to create problems to others.
“But we are used to it because we’re in the Europa League and that is a competition that creates more difficulties – we know that, Southampton know that and Tottenham will find out.”
Mourinho has a fully fit sqaud to choose from with the exception of defender Luke Shaw, who is still unavailable with a groin injury.
“It’s good for us to have everyone available, but Luke Shaw and he’s not far,” said Mourinho.
“Central-defender position we have now all of them, Chris Smalling is back, Eric Bailly is back, Daley Blind is fine, Marcos Rojo is fine.
“It’s a position where it’s important to have stability in options. We were in a difficult position a couple of months ago, but now we’re safe.
“We know Bailly is going to the Africa Cup of Nations in January, but for the next three matches we know what we have.”