The Pixar movie, which features the voice of Scottish actress Kelly Macdonald as the heroic Princess Merida and first female lead in the company's history, bumped Madagascar 3: Europe's Most Wanted to second place with takings of $20.2 million (£12.6 million).
Debuting in third is fantasy horror film Abraham Lincoln: Vampire Hunter with earnings of $16.5 million (£10.3 million) and in fourth is sci-fi epic Prometheus ($10 million/£6.3 million). Tom Cruise's musical Rock of Ages rounds out the top five with $8 million (£5 million).
Steve Carell and Keira Knightley's new apocalyptic comedy Seeking a Friend for the End of the World failed to set the chart alight - it premiered at number 10 with $3.8 million (£2.3 million).
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