After taking a substantial dip last weekend, the box office is expected to rebound this weekend with a likely tight race between three new releases. Box office analysts disagree about which one will rise to the top, but overall, the sci-fi drama Knowing , starring Nicolas Cage and Rose Byrne, appears to have The Edge. Nevertheless, they note, prerelease buzz has been hot for I Love You, Man, starring Paul Rudd and Jason Segal (who also starred in last year's Forgetting Sarah Marshall . Finally, there's universal's spy story Duplicity , starring Clive Owen and Julia Roberts in her first starring role in five years. Industry watchers regard the movie as a test of her reputation for being Hollywood's biggest female box-office draw.