While Bieber fever could break out among the nation’s teen girls as Paramount’s 3D “Justin Bieber: Never Say Never” opens at 3,105 locations, most B.O. observers are expecting Adam Sandler fans to give an edge to Sony’s Sandler-Jennifer Aniston romantic comedy “Just Go With It” at 3,548 locations.

“Just Go With It” won’t benefit from a Valentine’s Day boost this weekend (the holiday falls on Monday), but the comedy is expected to hold enough sway among broad demos, including couples, to beat “Bieber,” even with the latter pic’s 3D upcharge. “Never Say Never” is opening in 2,516 3D-equipped locations.

Both pics will compete for aud attention with other wide releases: Disney’s 3D toon “Gnomeo and Juliet” and Focus Feature’s swords-and-sandals epic “The Eagle.”

Fox Searchlight bows Ed Helms laffer “Cedar Rapids” in limited release today. Pic, which received largely upbeat critical response coming out of this year’s Sundance Film Festival, launches at 15 domestic engagements.

Some overseas auds will get the weekend’s wide releases day and date. “Just Go With It” bows in Mexico and the U.K.; “The Eagle” starts in Russia, while Disney will wait until next weekend to launch “Gnomeo” in that territory. The toon goes day and date in Blighty through local distrib Entertainment One.

The domestic B.O. has been in a slump of late, down 24% from 2010, and without Valentine’s Day to entice couples over the weekend, the market should stay down this weekend.

Warner Bros.’ “Valentine’s Day” ruled the same frame last year, with $56.3 million, followed by Universal’s “The Wolfman” and 20th Century Fox’s “Percy Jackson and the Olympians: The Lightning Thief,” both of which saw north-of-$30 million weekend takes.

According to B.O. pundits, “Just Go With It” should land in the high 20s — a solid but not stellar start for Sandler.

But Sandler pics consistently prove play well into holdover frames. The thesp’s latest outing, “Grown Ups,” scored $40.5 million for Sony during its summer berth and became Sandler’s best-ever worldwide grosser with $217 million. Domestically, the film grossed $162 million, just behind 1999’s “Big Daddy” ($163 million).

Budgeted at $80 million, “Just Go With It” should benefit from its Sandler-Aniston one-two punch, as well as a less-restrictive PG-13 rating. Sony positioned the film to play through next week’s long President’s Day weekend, starting with a sizable Monday boost thanks to Valentine’s Day.

Par is banking on young girls and parents to lift “Never Say Never’s” weekend tally. The film is expected to launch near the mid-teens, but that may be a conservative prediction depending on the pop phenom’s popularity with young femmes. In hopes of building word of mouth among that core demo, Par held exclusive sneak previews on Wednesday priced at $30 a ticket and including special “Never Say Never” merchandise. Tickets went on sale Nov. 29 and sold out in several days to weeks, depending on the region, according to the studio.

The biopic-music concert hybrid cost $13 million, meaning Par should ultimately have a profitable venture on its hands. “Never Say Never” is the inaugural outing for Par’s newly formed micro-budget arm Insurge Pictures.

Disney’s 3D offering this weekend, “Gnomeo and Juliet,” which opens at 2,725 U.S. locations, including more than 1,800 in 3D, may have broader family appeal than “Never Say Never,” but the toon will likely see fewer 3D ducats sold as parents have been less willing to shell out the premium price for the whole family.

The long-gestating toon started with the Mouse House but eventually went to Miramax as the label’s first inhouse toon. After Miramax shuttered, “Gnomeo” reverted back to Disney and will go through its Touchstone Pictures banner.

“Gnomeo,” with the voice talents of James McAvoy and Emily Blunt, adapts a “Romeo and Juliet” storyline with garden gnomes as the titular characters. Elton John provided original songs for the toon, which became a big selling point for Disney in the pic’s promotional materials.

Meanwhile, Focus’ Channing Tatum starrer “The Eagle,” an inhouse production for the specialty label, is expected to fall somewhere behind the weekend’s other wide releases, with a bow of $6 million-$9 million likely. That would be a good start for “The Eagle,” said a Focus rep.

The film, which opens at 2,296 locations, appeals mostly to males, with a strong contingency among females drawn to Tatum. Thesp has been particularly active in promoting the film during publicity tours in the U.S. and abroad. U is distribbing the film in the U.K. and Australia.

In limited Stateside release, this year’s Oscar-nominated short films will get their usual theatrical run through distrib Shorts Intl. The program launches today at an aggressive 95 locations.

Also, Sony Pictures Classics expands “The Illusionist” to 206 locations, up from 68 last weekend. Toon, which has cumed $766,312 since bowing Dec. 25, received an Oscar nomination for animated feature.