A scene from Monsters University Photo: IC

Animated prequel Monsters University took home its second US and Canadian box office title with $46.2 million in ticket sales over the weekend, fending off a red-hot debut from Sandra Bullock and Melissa McCarthy in female buddy comedy The Heat.

Outpacing industry projections, The Heat nabbed $40 million from Friday through Sunday and finished in second place, according to studio estimates.

Big-budget, explosion-filled White House Down fell short of expectations with $25.7 million in its first three days, finishing the weekend in fourth place.

Hollywood forecasters had predicted each of the new films would haul in at least $30 million over the weekend.

Zombie thriller World War Z, starring Brad Pitt as an ex-UN crisis specialist fighting the undead, slipped just one notch to third in its second week in release, earning $29.8 million over the weekend domestically. That brought its global total to $259 million.

Family crowds kept Monsters University at the top of the charts following a big debut a week earlier, when it became 14th consecutive film from Walt Disney Co's Pixar unit to open at No.1 on North American charts. Combined with global sales, the movie's tally through Sunday crossed the $300 million mark, Disney said.

The prequel to 2001 blockbuster Monsters Inc. features the voices of Billy Crystal and John Goodman as monsters who flunk out of the college's scare program.

Reuters