Adam Sandler, one of the most dependable box-office stars over more than the past decade, will be facing unpredictable competition from the reigning teen idol and a pair of garden gnomes this Valentine's Day weekend, and all bets are off on how he'll do. Several forecasters predict that he'll again come out on top with his latest film, Just Go With It , which costars Jennifer Aniston, but they suggest that he won't pull in as much as usual -- probably around $30-35 million versus $40.5 million for last year's Grown Ups and $39.9 million for 2004's 50 First Dates . His principal competition comes from the Justin Bieber concert documentary Never Say Never, whose target audience is his tween-to-teen fan base, but his recordings have also proved popular with older consumers as well. Two similar concert docs provide mixed guidance on how well the Bieber flick will do. Miley Cyrus's opened on a limited number of screens and a limited engagement in 2008, taking in $31.1 million on its first weekend on just 683 screens. But the following year, The Jonas Brothers' 3D Concert Experience sold just $12.5 million worth of tickets during its opening weekend, despite having twice the number of screens and the 3D surcharge going for it. The other major competition comes from Disney's Gnomeo & Juliet , which is expected to draw a big family audience. Curiously, although it's a G-rated animated feature, it's not being released under the Disney banner but its almost-defunct Touchstone label, an apparent move to distance itself somewhat from an animated film that was produced neither by Disney's Burbank animation unit nor by Pixar's in Emeryville -- but by Starz Animation in Toronto. Yet a fourth newcomer is Focus Features' The Eagle , aimed at men who enjoy Gladiator movies, which analysts suggest will be lucky to crack $10 million.