Both they and Manchester City have been accused of recklessly buying their way to success because of the vast sums involved but Mourinho doesn't think it provides any guarantees in itself and says Tottenham, who have not spent anything in this window, are also challengers.
"Of course to buy lots of good players is important and better squads are better equipped to win the title. That is normal but not enough," he stresses.
"I think every one of us in his own way is equipped to do it. I think Tottenham without any spending is equipped to win the title because they have fantastic team, fantastic manager, great stability and have been together for a long time.
"Man City, fantastic manager, great spending, already very good players, are equipped. Arsenal the same, they didn't sell the top players like Ozil, Alexis, that some expected. Liverpool is equipped. Chelsea were the champions easily, they lost some players but bought some players. I just think the competition can be better than ever."