Before it was a viral sensation and a ratings boon for Spike TV, “Lip Sync Battle” was just a segment on “The Tonight Show With Jimmy Fallon.” So, why would any A-List star sign on for a full show dedicated to celebrities pretending to sing?

“There were a lot of people that we called initially that loved the idea and were so supportive, but just couldn’t quite wrap their head around doing it in the first season,” Casey Patterson, executive producer of “Lip Sync Battle,” told Business Insider. “You’re asking people who don’t sing for a living to come out and do that, and they couldn’t quite get there."  

A few months later, the story is very different. 

“They were watching. They were waiting to see it, and now we’re hearing from all of those people,” added Patterson, who also acts as Viacom Entertainment Group’s talent development and production executive.

Hosted by LL Cool J and Chrissy Teigen, “Lip Sync Battle” pits stars against each other in two rounds of karaoke — one stripped down performance and the other turned up. Its premiere was watched by 2.2 million people and became Spike's most-watched unscripted program ever. Last week, it was renewed for a second season.

Its first season has included such big-name contenders as Dwayne Johnson, Anne Hathaway, Emily Blunt, Michael Strahan, Anna Kendrick, and Jennifer Lopez.

How did it get so many A-listers to shed their inhibitions and take the stage? That didn’t come easy and took a huge group effort, some long nights, and several favors. 

BI spoke with one of the show's executive producers and its director to find out.

1.) They hit up their famous friends.

When “Lip Sync Battle” began production, it was still an untested concept. As a guest segment on “The Tonight Show,” it had yet to be introduced. And its breakout viral Emma Stone moment was months from happening.

“Everyone called their friends, absolutely, and it was a family affair, 100% every single person around the table, including myself,” Patterson remembered. “LL Cool J was calling all of his friends.”

“He was making calls at two o’clock in the morning,” interjected director Beth McCarthy-Miller, whose credits include 'SNL’ and dozens of half-hour comedies. 

2.) They kept their famous producers close.

When your executive producers include Fallon, John Krasinski (“The Office”) and Stephen Merchant (“Hello Ladies”), it’s nice to keep them close.

“We had to earn the trust of the talent community, because we’re asking a lot,” Patterson said. “We’re asking them to come up and potentially make fools of themselves and to really commit to it, and I think he reason it worked is because everyone around the table showed up. All the partners showed up. Everyone was there producing. John Krasinski was backstage… he actually produced the backstage package for Anne Hathaway.”

At the same time, Spike had something to prove to the show's producers and were willing to do whatever it took to make the show a success.

"Spike wouldn’t be the first thing you think of when you think of lip-sync battling," Patterson said. "There are so many outlets and so many places that you can go and it was very forward thinking, and a big leap of faith, that those guys chose us. Rick Schwartz and Jay Peterson brought it to us and we were very [appreciative]."

3.) They let the stars choose whatever songs they want, no matter the cost.

The show definitely could have saved some money by making the stars pick from a selected book of songs, but producers decided not to curtail song choices.

“It’s not an inexpensive proposition because of the music,” Patterson pointed out.

“It’s already the toughest ask in Hollywood,” she added. “It’s moving so far outside their comfort zones that they need the level of comfort that they can pick their own songs, they need that level of comfort. We’re not going to musicians, for the most part, we’re going to celebrities who don’t sing for a living.”

4.) They made the experience easy.

Hathaway, for example, was rehearsing for her one-woman off-Broadway show, “Grounded,” and told the lip sync show's producers she’d be limited on time. So, the team got to work.

“We brought our choreographer, Danielle [Flora], who is unbelievable,” said McCarthy-Miller. “She works at ‘SNL’ as well, and she knows how to do as minimal or as much and be able to teach it to somebody quickly just to kind of help formulate the performances. It was a perfect storm of everybody and it was really one of those Mickey Rooney-Judy Garland movies. Everybody was like, ‘OK, I can do this. All right. I’ll go get a wig. OK, here’s some costumes.’ It was everybody totally engaged in wanting to make the show awesome.”

5.) They chose the right director.

McCarthy-Miller has taken everything she has learned from “SNL” and other projects in order to apply them here.

"Aside from how much I love Beth and our friendship, I really felt like there’s isn’t anyone else who knowing that we’re going to have a limited amount of time with people, and where we need to get them,” Patterson said. “She’s really the only person I could think of that is capable of that and at such a level that you’re seeing the results of that." 

McCarthy-Miller stood in for Madonna with Fallon while they waited to hear if she’d make a cameo during his performance of “Like a Prayer” and later joined his conga line. She also sang “Material Girl” for Taraji P. Henson at least 10 times so she could concentrate on choreography without playing the actual music. 

“I was just trying to help,” the director explained.

See some performances from the show below:

Hoda Kotb performing "Baby Got Back."

Anna Kendrick's “Booty” (with JLo) vs. John Krasinski's “Proud Mary”

 Dwayne Johnson's "Shake It Off" vs Jimmy Fallon's "Jump In The Line"

NOW WATCH: Jimmy Fallon's new lip sync show looks hilarious

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SEE ALSO: Why everyone is suddenly obsessed with Spike TV's new show 'Lip Sync Battle'