NASHVILLE, Tenn. -- The king of selfies, at least among NFL quarterbacks, got a little wake-up call from one of the best defensive players in the NFL on Sunday.
After the second sack, Watt's celebration imitated the rookie quarterback taking a photo of himself -- a selfie, as Mettenberger loves to do.
"It's just kind of a reminder, this is the National Football League, not high school," Watt said. "Welcome to the show."
Mettenberger was named the starter on Thursday, when a photo of him during his first interview as the Titans starter went viral. It featured his shaggy hair, mustache and a red headband in the style of Ben Stiller's character in the movie "Dodgeball."
He posted what he called a "stacheselfie" on Friday, emphasizing his mustache, and shortly thereafter, yet another cellphone self-portrait of his newly cut short hair as he sat inside his car.
"If I was a rookie quarterback being named the starter for the first time in the league, I feel like I'd be a little bit more focused than that. Maybe he'll learn from it, maybe not."
J.J. Watt, on Titans rookie QB Zach Mettenberger posting multiple selfies
this week on social media
"The plan was always to clean myself up when I was named starter," he said. "That came a little sooner than I anticipated. With media coming, I wasn't able to get a haircut, so I thought I'd have fun with it.
"Ultimately that's what this game is about -- it's about having fun. Any time you get an opportunity to show some character or personality, you've got to make the most of that."
What might have annoyed Watt the most was a selfie taken Sunday morning and posted about 90 minutes before kickoff.
"I just, I take my job very seriously," Watt said. "If I was a rookie quarterback being named the starter for the first time in the league, I feel like I'd be a little bit more focused than that.
"Maybe he'll learn from it, maybe not. We won the game, so that's all that matters."
ESPN.com Titans reporter Paul Kuharsky contributed to this report.