In the battle for Millennials with the midnight munchies, who’s going to win out?

In one corner you have 56-year-old fast-casual heavyweight Denny’s. Standing opposite, at 47 years old, is Yum Brands’ fast-food stalwart Taco Bell. Odds-makers might give the nod to the Bell, as Denny’s continues to lose late-night customers who prefer to "think outside the bun."

But before you place your bets, check this out—Denny’s has a little star power for a cornerman. For the last year, the chain has run its "Allnighter" program, which adopts up-and-coming musicians, provides them with $1,000 in Denny’s gift cards and invites them to create special late-night menu options. Denny’s then uses its social media platforms to advertise the bands’ after-parties and menu items. Alumni include Rascal Flats, Katy Perry and Good Charlotte.

Not to be outdone, however, is the creator of the "Fourthmeal,"—for those who can’t face the foodless hours between dinner and breakfast. Taco Bell’s latest campaign features the video, "It’s All About the Roosevelts," which debuted in movie theaters last week airing before "Transformers: Revenge of the Fallen." With "Saturday Night Live"’s Andy Samberg and his "Digital Shorts" as its muse, the video features a rap star talking-up the chain’s late-night menu, which can be purchased for only a few "Roosevelts," or dimes.

Both campaigns are heavy on the social media—each features its own microsite—including video downloads, Twitter campaigns and mobile apps. So, this is sure to be a tough bout. Denny’s has the celebrities, but Taco Bell has the reputation. Only time, and the much sought-after youth market, will tell.

Let’s get ready to rumble!