The Blancos boss acknowledges that Real Madrid's hopes of group-stage progression lie not just with overcoming Manchester City, but the Bundesliga champion as well.
The Portuguese praised the progress exhibited by the German champion over the past couple of seasons, and maintained Los Blancos would have to be wary of their opponent's capabilities.
"I'm not sure [if Manchester City are our biggest opponents]. Borussia Dortmund have been champions of Germany twice in a row," cautioned the 49-year-old to AS. "They are well organized and very experienced, with many international-caliber players from Germany, and the top two from Poland. Their stadium and fans are impressive too."
Mourinho then aimed a sideswipe at Roberto Mancini's Premier League winning side, claiming all the money in the world would not necessarily buy the club European success.
"The Abu Dhabi investors have invested so much, because they want to ensure the European Cup does not slip out of their hands," the former Chelsea boss added. "Nevertheless, the tradition of clubs such as Real Madrid, Barcelona, and Bayern Munich cannot be bought. The best players in the world will always go there."
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