The Stamford Bridge outfit defeated Southampton 3-1 on Sunday and picked up three points on their travels in a thrilling 4-3 victory over bottom club Sunderland on Wednesday.
Chelsea will once more take to the road on Saturday when they take on Stoke City at the Britannia Stadium, before welcoming Steaua Bucharest to Stamford Bridge for their final UEFA Champions League group stage fixture four days later.
Mourinho believes it is no coincidence that some sides have been handed three games in eight days, while his club have had less time for recovery.
"This week was a hard one. We started on a Sunday, not a Saturday, playing against Southampton and finishing on Saturday (at Stoke)," said the Portuguese.
"For some clubs it's Saturday to Sunday, for us it's Sunday to Saturday. For us, again, when it comes to fixtures we are in trouble.
"(It would be) a big coincidence; it's always the same teams; the situation always benefits the same teams. We have had three matches, two of them consecutive away. We have to cope with it and give a big effort.
"I don't like to give a day off before a Champions League game, but I'll give the day off on Sunday. It's good for their heads; I like the players to recover from a physiological point of view but mentally (it) is more important."
Chelsea stayed four points behind league leaders Arsenal courtesy of their win at Sunderland, while Manchester United lost further ground on the leaders with a 1-0 defeat against Everton and are now 12 points off the pace.
Mourinho still expects David Moyes' men to be among the challengers for the title.
He added: "If it's another club (other than United) I would tell you it's impossible. With Manchester United I don't say that. The potential and the culture of the club is not one to panic.
"They are still a contender; they will stick together, win five or six matches and they will look to other matches where teams will lose points.
"In relation to Arsenal - if they lead, it's because they were better, made less mistakes. So they deserve to be there. But the championship doesn't end at the end of the year, it ends at the end of May."
The Portuguese also confirmed left-back Ashley Cole will feature from the start against Stoke or Steaua, with his last start having come in the 2-0 defeat at Newcastle on November 2.
