We predicted a $40-45 million opening for Seth Rogen's 'Neighbors', but the frat-comedy co-starring Zac Efron obliterated expectations to pull in $51 million and win the top spot at the box-office by $14 million. The well-received comedy dumped The Amazing Spider-Man 2 into second place - the sequel took $37 million.

NeighborsZac Efron In 'Neighbors'

Rogen's raunchy comedy has also soared overseas, grossing $34.4 million from 29 countries and placing at No.1 in 17 of those, including Australia, Germany and the UK. The success kicks off Univeral's summer in true style and gives a boost to Seth MacFarlane's comedy A Million Ways to Die in the West, which rolls out in three weeks.

Directed by Nick Stoller - the man behind the excellent The Five-Year Engagement - Neighbors actually pulled in a 53% female audience, which is unusual for a raunchy comedy.

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Universal domestic distribution chief Nikki Rocco emailed with Seth Rogen and the other filmmakers throughout the weekend. "They never expected this kind of opening. Seth is beyond thrilled," she said.

Elsewhere at the box-office, the Cameron Diaz/Leslie Mann/Kate Upton comedy The Other Woman held onto third place, and Heaven is For Real and Captain America: The Winter Soldier rounded out the top five.

Neighbors will probably have to concede the No.1 spot to Godzilla next weekend, though could hang onto No.2 ahead of Million Dollar Arm with Jon Hamm and The Immigrant with Joaquin Phoenix.  

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Watch the Neighbors red-band trailer: