It was a '90s flashback last night at the 2012 NFL Kick-Off Concert -- where Gwen Stefani and Mariah Carey proved they're both getting better with age.

Gwen went back to her ska roots for the show, looking just like she did back in No Doubt's "Just a Girl" heyday. Not too shabby for a 42-year-old, right?

While Gwen's stomach looks incredible, she recently told Harper's Bazaar that it's not easy to maintain -- saying "There is no secret: You just have to eat healthy, work out, and torture yourself!”

But Gwen wasn't the only one who looked great -- take a glimpse at Mariah's gams!

While her tacky outfits are still questionable for a 42-year-old, there's no denying Mariah looked great ... especially for a mother of one-year-old twins.

Check out more photos from the kick-off concert above, including a couple adorable shots of Mimi and her cute Jack Russell Terrier!

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