Director Bryan Singer has assembled two -- not one, but two -- of the greatest mutant hero teams ever seen for the upcoming sequel "X-Men: Days of Future Past," but there may be little interaction between the two temporally-separated groups.

"Days of Future Past" is based on the beloved comic book storyline of the same name, which involves alternate timelines and changing continuity, prompting the possibility that James McAvoy (Professor X in "First Class") and Patrick Stewart (who played an older version of the same character in "X-Men" 1-3) would be seen fighting side-by-side.

However, McAvoy has revealed that the young and old versions of the wheelchair-bound Xavier probably won't face down Magneto together.  

"It’ll be cool, but I don’t think [Stewart and I] get any scenes together, sadly," McAvoy told Empire [via CBM]. "I don’t think there’s any future self talking to past self."

"First Class" stars McAvoy, Michael Fassbender, Jennifer Lawrence, and Nicholas Hoult are all returning, along with the stars of Singer's first two "X-Men" films, including Stewart, Ian McKellen, Hugh Jackman, Anna Paquin, Shawn Ashmore, and Ellen Page (first seen in "X-Men 3: The Last Stand"). 

"Game of Thrones" stars Peter Dinklage will also star in the film as an unspecified villain. 

"X-Men: Days of Future Past" hits theaters July 18, 2014.