As NFL matchups go, this one is a classic: unstoppable offense against impenetrable defense.
FILE- In this file photo taken Dec. 19, 2011, San Francisco 49ers head coach Jim Harbaugh reacts against the Pittsburgh Steelers in an NFL football game in San Francisco. Harbaugh has become the favorite for Coach of the Year by doing things his way from Day 1. He doesn't care about making friends in the NFL or being popular among his peers. The 49ers, a Super Bowl contender this season, head into Saturday's, Jan. 14, 2012, home playoff game against Drew Brees and the New Orleans Saints as an underdog, just as he likes it.
Denver Broncos quarterback Tim Tebow (15) celebrates after beating the Pittsburgh Steelers 29-23 in overtime of an NFL wild card playoff football game Sunday, Jan. 8, 2012, in Denver.