Marvel's giant summer blockbuster Guardians of the Galaxy is officially the biggest movie of the year so far after it took $16.3 million over the Labor Day weekend to take its overall domestic taking to $274.6 million. Guardians has now surpassed Captain America: Winter Soldier as the highest-grossed movie of 2014.

Guardians of the GalaxyChris Pratt in 'Guardians of the Galaxy'

Michael Bay's Transformers: Age of Extinction - released in June in the U.S - remains top of the worldwide list with over $1 billion in sales. Guardians has earned $547.7 million around the globe.  

More: Robert Downey Jr calls Guardians of the Galaxy "best Marvel movie"

"This summer was placed in the unfortunate position of being the follow-up to the biggest revenue generating summer of all time," said Paul Dergarabedian, senior media analyst at Rentrak

"One or two movies can make all the difference," he said, noting that Iron Man 3 took $400 million last summer, more than any movie this year. 

InterstellarCan 'Interstellar Steal Guardians' crown?

Elsewhere this weekend, Teenage Mutant Ninja Turtles took second place with $11.8 million and YA adaptation If I Stay - about a girl who has an out of body experience after a car accident - took third place with $9.3 million. 

The horror flick As Above, So Below had to settle for fourth place, pulling in $8.3 million while Pierce Brosnan's poorly reviewed action-thriller The November Man took just $7.7 million. 

More: Nobody knows why 'The November Man' is called 'The November Man'

It seems the only movie likely to beat Guardians of the Galaxy is Christopher Nolan's Interstellar. The secretive sci-fi project stars Matthew McConaughey, Anne Hathaway and Jessica Chastain and apparently follows a group of scientists using wormholes to surpass the limitations on human space travel and conquer the vast distances involved in an interstellar voyage. It hits on November 7, 2014. 

Watch the 'Interstellar' trailer: