By Lisa Richwine and Chris Michaud

LOS ANGELES/NEW YORK, May 25 (Reuters) - The "X-Men" mutant superheroes smashed into U.S. and Canadian theaters and collected $90.7 million in ticket sales through Sunday, keeping monster hit "Godzilla" at bay and heading toward a decisive win over a long holiday weekend.

"X-Men: Days of Future Past" was expected to bring in $110 million by the end of the U.S. Memorial Day holiday on Monday, distributor 20th Century Fox said. The movie has already earned a global total of $261.8 million after opening at No. 1 in all 119 countries around the world.

Last week's winner, monster movie remake "Godzilla", dropped to second place with $31.4 million through Sunday, according to estimates from box office tracking firm Rentrak. Its sales were projected to reach $39 million by Monday.

Romantic comedy "Blended" claimed the No. 3 spot, taking in $14.2 million and on pace for about $17 million through Monday.

"X-Men: Days of Future Past" is the seventh movie in the blockbuster Marvel Comics franchise about mutant superheroes.

In the latest installment, Hugh Jackman's sharp-clawed Wolverine travels back in time to try and save the mutants from future destruction. To alter history, he is drawn into battle with the blue, shape-shifting Mystique, portrayed by Jennifer Lawrence in the $200 million film.

The movie scored the fifth-biggest Memorial Day weekend opening in history, Rentrak said.

"Godzilla," a remake of the classic 1954 Japanese monster movie, stars Aaron Taylor-Johnson as a naval officer who battles the rampaging beast.

"The film is holding strong even with huge competition in the marketplace and will have just under $160 million in North America through Monday," said Paul Dergarabedian, senior media analyst at Rentrak.

"Blended" reunites Adam Sandler and Drew Barrymore as single parents who have a bad blind date, then find themselves staying at the same African resort with their kids.

Rounding out the chart leaders, the Seth Rogen comedy "Neighbors" landed in fourth place with $13.9 million. Superhero sequel "The Amazing Spider-Man 2" was fifth with $7.8 million.

"X-Men" was released by 20th Century Fox, a unit of Twenty-First Century Fox. "Godzilla" was produced by Time Warner Inc's Warner Bros. and Legendary Pictures.

Warner Bros. also released "Blended." Universal Pictures, a unit of Comcast Corp, released "Neighbors." Sony Corp's movie studio distributed "Spider-Man 2." (Reporting by Lisa Richwine and Chris Michaud; Editing by Lynne O'Donnell)