Who could have predicted that the world’s next great TV format would be tossed off in a late-night talk show segment?

In a May 2013 airing of “Late Night With Jimmy Fallon,” the host stepped to the mic to face off against guest John Krasinski, fresh off his stint on “The Office.” The competition: lip syncing. Fallon opened with Melissa Manchester’s “Don’t Cry Out Loud”; Krasinski responded with Katy Perry’s “Teenage Dream.” And a format (eventually) was born.

Now, with new hit entertainment shows thin on the ground at TV markets, Viacom’s “Lip Sync Battle” is proving that simplicity can pay dividends.

“Over the last 20 years, I’ve been involved in selling a lot of formats, but shows that skyrocket like ‘Lip Sync Battle’ don’t come along that often,” says Caroline Beaton, Viacom’s VP of international programming sales.

Beaton launched the show at Mip last year, closing several deals including a multi-territory contract with Zodiak, mostly for European versions.

“Nine territories across [four] continents have now licensed the format,” Beaton says. These include Canada, Norway, China, Poland, the Philippines and across Africa, where the show is produced in Johannesburg. In the U.K., “Lip Sync Battle” bowed on Viacom-owned Channel 5 in January, where it competes on an even level with “Celebrity Big Brother,” averaging around 2 million viewers.

Viacom is looking to close more deals around the Mip TV confab, which runs April 4-7 in Cannes.

“ ‘Lip Sync Battle’ is a very uncomplicated show. It doesn’t set out to do anything but entertain,” says executive producer Casey Patterson.

The format sees two celebrities compete against each other, each lip-syncing a favorite song — usually with elaborate costumes and choreography — in front of a live audience. Audience reaction decides who walks away the winner. “It’s the antithesis of shows like ‘The X Factor’ and ‘The Voice,’ ” says Beaton.“ ‘Lip Sync’ kind of debunks the traditional view of stardom, and allows [them] to perform a song like they’re singing and dancing along at home with the radio on. Viewers respond to seeing celebrities performing against type.”

It’s also good for stars’ personal branding. “In an online world, fans expect to have a different kind of access to celebrities, and this show gives them that,” says Patterson, who helped develop the format which has become a genuine pop-culture phenomenon in the U.S.

Top Clips
Online “Battle” views
$33m Dwayne Johnson’s “Shake It Off” vs. Jimmy Fallon’s “Jump in the Line”
$28m Channing Tatum’s “Run the World (Girls)” vs. Jenna Dewan-Tatum’s “Pony”
$19m Anne Hathaway’s “Wrecking Ball” vs. Emily Blunt’s “Piece of My Heart”

The American version, hosted by L.L. Cool J with co-host Chrissy Teigen, airs on Viacom’s youth-skewing Spike, and has had street cred from the beginning, attracting big names such as Beyonce, Jennifer Lopez, Justin Bieber, Chris Pratt, Dwayne Johnson, Channing Tatum and Anne Hathaway. Averaging 4.7 viewers, it’s the top-rated show in the history of the 16-year-old network. Season two was the No. 1 TV show in the U.S. among 18- to 49-year-olds in its time slot, according to Viacom.

Even though “Lip Sync’s” creators — Krasinski, writer Stephen Merchant and Fallon — initially pitched the concept to NBC, they wanted to produce a show that, from the outset, had a life beyond linear TV. NBC passed, but Spike immediately saw the program’s potential.

“ ‘Lip Sync Battle’ is very shareable,” says Patterson. “That was always our intention. We wanted a show that would go viral.”

The noise generated by the program on social media following its April 2015 U.S. bow is just as valuable as traditional ratings. “ ‘Lip Sync’s’ been a social-media phenomenon,” Beaton says. “Clips from the show went viral immediately.” For instance, Hathaway’s channeling of Miley Cyrus singing “Wrecking Ball” on Spike has garnered 19 million YouTube views. “You can’t get better publicity than that when you’re trying to sell a format,” Beaton adds.

Patterson insists the show possesses genuine longevity. “We’ve only started to scratch the surface,” she says. “There’s always new music and new celebs emerging, so I think ‘Lip Sync Battle’ could run forever.”

And she muses about theming shows around the Olympics, or politics.

A “Lip Sync Battle” between Hillary Clinton and Donald Trump? That might send Spike into ratings orbit — and break the Internet.