A lovable pair of monsters won the box office this past weekend as Pixar's Monsters University pulled in $82 million, the studio's second-biggest opening behind Toy Story 3. Brad Pitt's zombie epic, World War Z, defied expectations to come in second with a $66 million haul. The thriller, which stumbled to the big screen with a number of production problems including delays and reshoots, was the best opening of Pitt's career. Last week's No. 1 movie, Man of Steel, was third with $41.2 million.