CHICAGO (CBS) — With Jason Campbell calling the signals tonight in San Francisco, coach Lovie Smith says the Bears won’t do anything differently on offense than they would if Jay Cutler was ready to play.

“Jason is a good football player, and we brought him in for this purpose,” Smith told WBBM Newsradio’s Josh Liss. “He will step in and do a great job.”

Smith said the formula for victory against the highly regarded 49ers is no different from past weeks: establish the run to open the passing game and count on some takeaways from the Bears’ defense.

Cutler was ruled out for tonight’s game after suffering a concussion against the Houston Texans. Smith said it’s important for the Bears to win a game against a top-ranked NFC team on the road.

LISTEN: Full Interview With Lovie Smith