Bayern take on Madrid in the first leg of their tie at the Bernabeu, and Robben believes that it is his former side, rather than the defending champions, who should be considered favourites to lift the trophy next month.
"We are no longer favourites," the Dutch winger told reporters. "Of course we want to win the Champions League again, but we're in the semi-final, and anything can happen.
"Real are the most dangerous opponent we could have faced."
Madrid have not won the competition since 2002.