X-Men: Days of Future Past” may soon become the highest-grossing film in the 14-year-old series’ history, providing another textbook lesson, as if one was needed, in the vital importance of the foreign box office to modern blockbusters’ bottom lines.

Domestically, the comicbook film and its $111 million Memorial Day kickoff will have to settle for second place in the series, behind the $122.9 million debut of 2006’s “X-Men: The Last Stand.” But its $302 million worldwide haul last weekend puts it in striking distance of a franchise record.

“There’s no question it’s going to be number one” in the series, said Phil Contrino, VP and chief analyst at BoxOffice.com. “It’s the impact of China. We’re rapidly heading to a point where China is close to mimicking Hollywood on key blockbusters.”

China’s burgeoning box office was barely a glint in Hollywood’s eye when the first “X-Men” movie hit $296.3 million worldwide way back in 2000. Today, it’s nipping at the United States’ heels, seemingly ready to overtake it as the world’s largest B.O. market. China’s box office is expected to climb 25% this year to $4.49 billion, as theater construction continues at a dizzying pace across the People’s Republic.

“X-Men: Days of Future Past” is now on pace to clear $500 million at the worldwide box office, analysts say, eclipsing the $459.3 million “X-Men: The Last Stand” racked up in 2006 and surpassing the $414.8 million that “The Wolverine” amassed last summer.

To hit this mark, 20th Century Fox spent $200 million to assemble an all-star crew of mutants, bringing Hugh Jackman’s Wolverine back into to the X-fold after two solo adventures, and reuniting several iterations of X-Men, such as Jennifer Lawrence, Patrick Stewart, Ian McKellen and Michael Fassbender, in a time-traveling adventure.

The result was a reinvigorated franchise, after 2011’s “X-Men: The First Class” grossed a respectable, but not otherworldly, $353.6 million globally.

“This is going to be ‘The Avengers’ of the X-Men franchise,” said Jeff Bock, a box office analyst at Exhibitor Relations. “It’s exactly the springboard that Fox needed to make this series continue to matter.”

There’s one downside to all this global growth.

“The foreign box office is certainly important, but international distributors take a bigger cut,” said Tony Wible, a media and entertainment analyst with Janney Montgomery Scott.

Whereas domestic theaters and studios more or less split a film’s theatrical proceeds, some countries such as China only kick back 25% of ticket sales.

With this global loot, however, there will be more than enough treasure to spread around.