1 of 5
Paul Sakuma, Associated Press
San Francisco 49ers cornerback Tarell Brown (25) is congratulated by wide receiver Ted Ginn Jr. (19) and offensive tackle Joe Staley (74) after intercepting New Orleans Saints quarterback Drew Brees (9) during the second quarter of an NFL divisional playoff football game Saturday, Jan. 14, 2012, in San Francisco.

SAN FRANCISCO — With New Orleans poised to score on its opening possession, Donte Whitner delivered a crushing blow that knocked out running back Pierre Thomas and forced the first of five Saints turnovers.

San Francisco's hard-hitting, opportunistic defense set the tone in the 49ers' thrilling 36-32 playoff win the same way it has all season.

From Justin Smith and Aldon Smith harassing Drew Brees all day, to Patrick Willis and NaVorro Bowman shutting down the running game and Dashon Goldson making punishing hits and key plays from the secondary, the defense is the biggest reason for the resurgence in San Francisco that has the 49ers (14-3) back in the NFC championship for the first time since the 1997 season.