Are Seahawks fans the loudest fans in sports?

SEATTLE -- The 12th Man, the nickname given to loud Seahawks fans at Century Link Field, is known around sports. The noise from a roaring 12th Man has been compared to a roaring jetliner, or a out-of-control rock concert.

And it's a noise the 49ers got to know intimately Sunday.

"The energy is going to be incredible," said one fan before Sunday's game. "Like they say the 12th Man. We might just be the upset."

The Hawks clinched at least a wild card birth into the NFL playoffs with a 42-13 victory over the San Francisco 49ers Sunday Night at CenturyLink Field. The Hawks could still win the division if the 49ers lose to the Arizona Cardinals in their final game of the season and the Hawks win over the St. Louis Rams.

For Seattle sports fans, a guaranteed berth into the playoffs meant Christmas comes early.

"We've had some tough times here when it comes to sports," said one Seattle fan. "This is a Seahawks town. This is what these guys love."

The Seahawks' final regular season game will be against the St. Louis Rams Dec. 30 at CenturyLink Field.

By Kate Burgess