SciFiNow has posted an interview with "X-Men: Days of Future Past" director Bryan Singer, who states it's "not healthy" for people to compare Fox's X-Men franchise to the Marvel Cinematic Universe.

"They're both comic books and at some point you can expand the universes, that's where the comparison ends," Singer told SciFiNow. "It sounds defensive, and it is defensive, but only because people make comparisons between [X-Men: Days of Future Past] and The Avengers, which is ludicrous. The Avengers is a mash-up of massive single character franchises of incredibly familiar characters and Iron Man. And did I mention Iron Man? Oh, and by the way – Iron Man. They are huge, colossal franchises that are peppered with all these other characters that are, again, extremely famous and so yes, Fox will at some point synergize [the X-Men] characters and that process is slowly beginning, but it’s very different than taking movies that gross close to a billion dollars and then pushing them together into these giant broad movies. If you want to give me Robert Downey Jr. in a metal suit and have him join the X-Men, then yes, let’s go head-to-head [with Marvel Studios]."

Fox's X-Men was one of the first successful modern superhero films, predating Sam Raimi's first Spider-Man film by two years. While Fox's X-Men franchise started strong -- the first film grossed $157.3 million, which grew until 2006's X-Men: The Last Stand's $234.4 million gross -- it started sinking in 2009 with the critically panned X-Men Origins: Wolverine -- a trend which continued for X-Men: First Class and The Wolverine. While Singer's (who has withdrawn from most Days of Future Past promotion due to ongoing accusations of sexual abuse) assertion that a comparison to the Marvel Cinematic Universe and Fox's X-Men franchise are unwarranted may be valid, they certainly share an audience -- and it's perhaps telling that lifetime domestic gross for the X-Men franchise started sinking after the debut of Iron Man in 2008.

That said, analysts currently predict that Days of Future Past will bring in more than $100 million for its opening weekend, which has the potential to be the franchise's highest-grossing opening in its history. (X-Men: The Last Stand grossed $102.7 million for its opening weekend -- also during Memorial Day.)

X-Men: Days of Future Past opens Friday.