With five minutes left in the first half of last week's game against the Atlanta Falcons, Chicago Bears head coach Lovie Smith approached No. 2 quarterback Rex Grossman on the sideline with a fierce look in his eyes.

"Get ready," Smith told him.

Grossman assumed the starting role in the second half and played impressively in a 16-3 Bears win. His performance earned him top dog status this week and for the rest of the season, meaning the Packers will face a different quarterback than they did during their match with the Bears on Dec. 4.

Rookie Kyle Orton started that game, completing six-of-17 passes for 68 yards in the 19-7 Bears win. Although Grossman will quarterback the Bears on Sunday, it will not greatly change the Bears' offense or the Packers' preparation for it.

"Their offense is already in place," Packers Head Coach Mike Sherman said. "It's hard for them all the sudden to go in a different direction as far as scheme goes."

That scheme revolves around the running game. The Bears will rely on the NFL's ninth-ranked rushing unit anchored by Thomas Jones (1,168 yards) and Adrian Peterson (5.7 yards-per-carry).

"We're a running football team. I look to see what the run stats are first," Smith said. "I'm not really interested in passing for 400 yards."

With a rookie quarterback at the helm, Smith emphasized the run even more. After Grossman suffered a broken ankle during the preseason, Smith handed the keys to Orton. The fourth-round draft pick led them to a 10-4 record but performed ineffectively of late.

Enter Grossman. The 2003 first round draft pick administered a shot in the arm to the offense last Sunday, completing nine-of-16 passes for 93 yards after Orton struggled through a two-of-10, 12-yard-passing day in the first half.

"We needed a spark," Smith said.

Although the Packers will prepare to stop a smash mouth football team, they will face subtle differences with the more experienced Grossman running the show. Kabeer Gbaja-Biamila said Grossman delivers the ball more quickly while Aaron Kampman noted he has a slightly stronger arm than Orton. Because of his skills, the Bears could open up the offense a bit more.

"He's a competitor. He has a good arm and does good things," Sherman said. "They may throw a little bit more than they did."

Presenting another challenge is the limited amount of tape the Packers can use to study Grossman. Because of his ankle injury in 2005 and a season-ending knee injury in 2004, Grossman only has started six games in three years. And he has played with the team's current offensive personnel for one half of one regular season game.

"We don't know as much about him," Kampman said. "But we've played him before."

Indeed Grossman faced off against the Packers in Week 2 of last year and led the Bears to a 21-10 win -- their first in Lambeau Field since 2000. Grossman completed 10-of-18 passes for 132 yards, one touchdown and one interception. He developed goosebumps before the game and deemed it his most significant NFL win.

"It was one of those memories you never forget," Grossman said. "Anytime you get a Bears-Packers rivalry in Lambeau Field, playing against Brett Favre ... It doesn't get much better than that."

To prevent a repeat scenario from occurring, the Packers have analyzed the Bears and their new quarterback diligently. They, however, know the Bears will remain a run-oriented team, and stopping that rushing game could determine the ballgame.

"In the end you can't change who you are and what you are in a matter of two weeks," Kampman said.