Mourinho expects United to be the main competitors after spending more than £40m on a string of summer signings and with Carlos Tevez still a major target.
"They have money to spend. I know when Chelsea were spending lots of money everybody was jumping - I don't jump because other people spend. They can do what they want with their money. They are contenders for the title, of course.
"Arsenal have very, very good young players, but they are there without pressure. Not many people expect them to do anything and that can help.
"Also, it's just a personal opinion, but Tottenham can do well because they have more players in the England national team than anybody else.
"Robinson, King, Dawson, Lennon, Defoe and Bent are a very good group of players. They spend money, they kept all the important players they have - even Berbatov -so Tottenham can create a difficult situation for us."