Barcelona and Liverpool have been billed as the teams that holders Manchester United will want to avoid in Friday's draw for the quarter-finals of the Champions League.
But according to Cristiano Ronaldo, Bayern Munich could be every bit as dangerous opponents after running up a 12-1 aggregate win over Sporting Lisbon in the last round.
"Bayern are very strong," the United winger warned. "I watched them play against my old team, Sporting Lisbon, and I was very sad because I didn't expect Sporting to lose so heavily.
"But this can happen in football. Bayern are very good -- they have mature players, strong players, quick players... Franck Ribery and Miroslav Klose are very impressive.
"Bayern play like a team and they look very difficult to beat."
Friday's draw will feature four English clubs -- Arsenal, Chelsea, Liverpool and United -- Bayern, FC Porto and Spain's two survivors, Barcelona and Villarreal.