Liverpool F.C. are the only side in the top four who are not involved in European competition and Mourinho thinks it could be a crucial factor as he again stated his table toppers are not favourites for league glory in May.
"There are teams with more potential than others, obviously. There is another, like Liverpool, with a big advantage with the fact that they don't play in the Champions League," Mourinho told Britain's Sky Sports News on Thursday.
"Playing in this is going to take concentration and energy from the teams that are involved in it. I think it will be good fun.
"When I say we're not the top candidate everyone thinks 'here he is again, with what you like to call the mind games'. But it's just my feeling. The league is amazing - it is difficult for every one of us."
Chelsea could only draw 1-1 at lowly West Bromwich Albion on Tuesday and lead the table by a point from Arsenal, with Manchester City a further two points back and Liverpool one behind Manuel Pellegrini's men.
"Maybe we lost two points or won one point against West Brom and I think it will be like this until the end of the season," Mourinho said.
"All teams need points for their objectives - some for relegation, some for the Champions League - so the fight for points will be harder."
Mourinho also backed England manager Roy Hodgson's decision not to try to coax Chelsea captain John Terry out of international retirement for the World Cup after a solid season by the centre half.
"I'd never intervene. He (Hodgson) is in charge and has everything in his hand. He has made that decision," the Portuguese remarked.
"For me as a Chelsea manager I'm happy players play with their national teams - but at the same time I'm happy an important player like him is fully focused on his work at Chelsea."