CHICAGO – Rex Grossman energized the crowd, then warmed up the Chicago Bears’ offense with quick decisions and precise throws.

Grossman added a different dimension after relieving the struggling Kyle Orton in the third quarter, and the Bears rolled to a 16-3 victory over the Atlanta Falcons at frigid Soldier Field.

The projected starter before breaking his left ankle in a preseason game at St. Louis, Grossman completed 9 of 16 passes for 93 yards with an interception. It was plenty, though, with Chicago’s staunch defense shutting down Michael Vick and the Falcons as the Bears rebounded from last week’s 21-9 loss at Pittsburgh.

The NFL’s No. 1 defense limited the Falcons to 231 yards. The Bears increased their lead in the NFC North to two games over Minnesota, an 18-3 loser to Pittsburgh. The teams meet Jan. 1 in the regular-season finale.

Chicago (10-4) turned to Grossman after watching Orton complete 2 of 10 passes for 12 yards in the first half.

In his first regular-season game since Sept. 26, 2004, when he tore the ACL in his right knee at Minnesota, Grossman got off to a quick start.

He entered the game to a loud ovation after the Falcons (8-6) punted on the opening drive of the second half. And those cheers grew louder as he hit Muhsin Muhammad in stride over the middle for a 22-yard gain on the first play.

Grossman hooked up with Justin Gage and Muhammad again as the Bears drove to the Falcons 8. But on third down, he threw an interception – and the Bears got lucky.

Keion Carpenter picked off the pass near the goal line, then fumbled it. Gage recovered, and Thomas Jones ran it in from the 1, increasing the Bears’ lead to 13-3.

Robbie Gould’s third field goal, a 39-yarder, made it 16-3 with just under a minute left in the third period.

The Falcons were driving toward the end zone in the fourth quarter when Vick completed a pass to Michael Jenkins. Chicago’s Mike Green delivered a vicious hit, the ball popped up and Nathan Vasher intercepted it at the Bears 10.

The Falcons challenged, thinking Jenkins was down by contact. The interception stood and coach Jim Mora argued extensively, swiping his arm in the air, resulting in a 15-yard unsportsmanlike conduct penalty.

With the game-time temperature at 12 degrees and the wind chill at minus-3, the Bears were in their element. And they sent the Falcons’ playoff hopes plummeting.

After leaving last Monday’s victory over New Orleans with bruised ribs, he ran for just 35 yards and completed just 13 of 22 passes for 122 yards. He threw two interceptions.

Warrick Dunn carried 17 times for 81 yards.

For Chicago, Jones ran for 91 yards and a touchdown. Brian Urlacher had 11 tackles. Vasher and Green each had an interception, and Adewale Ogunleye and Tank Johnson had a sack apiece.

But the story was Grossman’s return. Bears coach Lovie Smith had said Orton would remain behind center, barring injury. But he saw enough in the first half to change his mind.

As the Falcons went three-and-out to start the second half, Grossman took snaps on the sideline with center Olin Kreutz. Then he did enough on the field to secure the win.

AP-ES-12-19-05 0002EST