MONDAY UPDATE: “Cowboys & Aliens” held off a ragtag band of upstart Smurfs to win the weekend box office, according to final numbers released Monday. “C&A” grossed $36.4-million in domestic ticket sales to edge “The Smurfs” ($35.6-million).

As the smoke clears in the firefight between cowboys and aliens, the body count is in. The result: One dead heat.

The underperforming “Cowboys & Aliens” and the exceeding-most-all-expectations “The Smurfs” wound up in a photo finish at the domestic box office, according to studio estimates announced Sunday. Meaning there’ll be suspense ‘round the B.O. corral when the final numbers come in Monday.

As of Sunday, each film had grossed $36.2-million in their weekend debuts.

Even if Jon Favreau’s “Cowboys” is able to edge “Smurfs,” it would be a hollow victory. The sci-fi western ever so loosely based on Scott Mitchell Rosenberg’s Platinum Studios comic had a posse of Hollywood heavyweights behind it, including not only Favreau but also such big guns as Damon Lindelof, Steven Spielberg, Brian Grazer and Ron Howard. Earlier, Universal reportedly hoped that the highly promoted film would gross at least $45-million.

Yet Harrison Ford’s grizzled gunslinger couldn’t readily outdraw another old-timer: Papa Smurf.

Sony’s turquoise-hued Smurfs have not only “Cowboys” singin’ the blues, but also the many pro critics who skewered the 3D animated film that reimagines the half-century-old comic characters.

“Cowboys” (also starring Daniel Craig and Olivia Wilde) may have drawn many lukewarm reviews, but “Smurfs” — according to reviews — is one of the worst films of the year. The little blue characters (featuring such voice actors as Hank Azaria and Katy Perry) get a “20” average rating on RottenTomatoes.com (where the audience rating, by comparison, is “65%”), and scores a mere “30” on Metacritic.com.

Perhaps Spielberg can take solace, though, that it just might be a good year cinematically for long-ago Belgian cartoonists. The “Schtroumpfs” were created in 1958 by cartoonist Pierre Culliford, better known by his nom-de-toon Peyo.

Late this year, Spielberg will release his performance-capture spectacle ”Tintin,” based on the boy-reporter adventures created by Belgian comic artist Hergé.

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Elsewhere, last weekend’s box-office champ, “Captain America: The First Avenger,” grossed $24.9-million to finish third. And fourth-place “Harry Potter and the Deathly Hallows — Part 2” grossed $21.9-million to cross the billion-dollar global-gross mark — one of only nine films to do so.

Writer/artist/visual storyteller Michael Cavna is creator of the "Comic Riffs" column and graphic-novel reviewer for The Post's Book World. He relishes sharp-eyed satire in most any form.