The First Avenger outmuscled its competition at the box office this weekend, including Harry Potter, and had the most forceful opening of any big-budget superhero movie released this summer.The 3D film, which stars Chris Evans as a puny military reject who is transformed into a superhero via a secret government programme, grossed a solid $65.8 million in the US and Canada.That was over $10 million more than both X-Men: First Class and Green Lantern collected upon their debuts in June, and just a tad above the $65.7 million opening weekend for Thor in May.
