Heading into the fourth quarter of album sales, retailers are understandably jittery.

So far this year, sales are down about 11 percent from 2007. But it's usually the crucial Oct. 1-Dec. 31 period that can often stanch the bleeding, simply because most superstar acts wait until the holiday spending frenzy to introduce product in stores or online.

These days, it's even becoming more common for top acts whose fans rabidly anticipate new material to release a single to iTunes months in advance of an album, then have those same fans re-buy the song when it's released as part of the album, and then have them purchase it one more time when the album is re-released in "deluxe" form with a few live covers or Christmas tunes tacked on.

So these early days of fall find radio stations inundated with new singles, as artists hope to create anticipation for their full-length product to come later in the season.

Here's a look at some just-released singles -- with a few surprising verdicts.

Nickelback, "Gotta Be Somebody" (from "Dark Horse," due Nov. 18)

Who knew it was possible for Nickelback to release a fantastic song? Thank Mutt Lange -- genius producer behind Def Leppard, AC/DC and soon-to-be-ex Shania Twain -- for infusing the Canadian band's generic, plodding rock with sweet melodies and a layered, soaring chorus that, no joke, might produce a little chill the first time you hear it.

The lyrics might be trite, but their hopefulness is sure to resonate with anyone who has ever suffered from a crushed heart. Expect to hear this one overplayed on radio well into 2009.

Grade: A

. . .

David Cook, "Light On" (from untitled debut, due Nov. 18)

No one expected -- or wanted -- Cook to stick to sentimental ballads like his Hey-mom-I've-just-won-"American Idol!" song, "Time of My Life." But this first single from Cook's upcoming debut is a disappointing indication of his future.

As nondescript as Chris Daughtry's self-titled band is, his songs at least have memorable hooks. This formless midtempo rocker from Cook sounds like a misguided attempt to mimic Seal's vocals, with a few leftover guitar strains from Alice in Chains' softer stuff thrown in behind his voice.

And let's not even discuss the ridiculous new photo that accompanies the single. Cook is scruffily adorable when he isn't being gussied up to look like the grandson of one of the members of The Cure.

Grade: C- (song), D- (the "look")

. . .

Britney Spears, "Womanizer" (from "Circus," due Dec. 2)

Well, it's better than her last couple of singles ("Gimme More" and "Piece of Me"), which sounded as glazed-over as Spears looked at the time.

MTV inexplicably embraced those robotic chants masquerading as songs, but that certainly doesn't make them suddenly viable.

On "Womanizer," her overly processed voice and the repetition of the song's title is quickly grating, but there's a spry swing behind the electronic beat that helps quell the urge to squeeze the life out of the hard drive just to shut her up.

Grade: C+

. . .

Keane, "Spiralling" (from "Perfect Symmetry," due Oct. 14)

On the first single from its third album, the British trio borrows a loose, shuffling drumbeat from Bowie, synthesizers from Depeche Mode and layered vocals from any'80s band worth its eyeliner.

So basically, it sounds like something off the Killers' first album. Which is a very good thing.

Most notable about the song is its judicious use of electric guitar, up until now an absent element in Keane's brand of mellifluous Brit pop.

Grade: B

. . .

Kanye West, "Love Lockdown" (from "808s & Heartbreak," due in November)

Say what you will about West's crybaby antics and pompous persona, but he's pretty proficient at reinventing his sound.

Nothing in "Love Lockdown" pops like the best of West's creations ("Stronger," "Gold Digger") and his trademark humor is absent. But even a serious West is a listenable one.

Grade: B-

. . .

Killers, "Human" (from "Day & Age," due Nov. 24)

Thankfully, the band's urge to be the next Springsteen was shoved out of its system on the last album ("Sam's Town"), so it can now comfortably resume its position as the Pet Shop Boys/Cure/London Suede of the'00s.

But what's with the chorus of "are we human or are we dancer"? It makes about as much sense as "the reflex is a lonely child waiting in the dark," which, come to think of it, didn't seem to hinder Duran Duran's career.

Grade: A-