Strange, from director Scott Derrickson, poses a challenge Marvel has faced before. It's always tricky to launch a franchise when a superhero movie doesn't feature a marquee character, although Marvel has a strong track record in this arena. Neither the first Thor ($65.7 million) nor the first Captain America ($65 million) debuted at the level of the original Iron Man ($98.6 million), but they successfully launched their own franchises, as did last year's Ant-Man. Robert Downey Jr.'s Iron Man has become one of the most bankable superheroes at the box office, but Tony Stark was also a lesser-known character when he first hit the big screen in 2008.

Still, if Doctor Strange opens below $55 million, it would mark the lowest start for any film in the MCU. (One of the major tracking services shows Doctor Strange debuting to $64 million or better, according to those with access to the data.)

Doctor Strange's tracking came Thursday, three weeks before it rolls out in theaters and ahead of Disney's final major marketing push.