It appears the Chicago Bears will get a quick verdict on whether they made a smart move by adding Michael Bush to their roster as a backup for Matt Forte.

Forte suffered a high ankle sprain Thursday night during the 23-10 Chicago loss to Green Bay that also saw Jay Cutler pummeled with seven sacks.

The early expectation is that Forte, a Pro Bowler who signed a four-year deal that includes $18 million in guaranteed money, will miss some playing time.

"That's why I'm here," Bush told the Chicago Tribune. "They brought me here to pick up where (Forte) left off, if something went wrong. It's the insurance plan, I guess. I'll be ready.''

Bush was in a similar situation in Oakland last season, where he took over for another marquee running back after Darren McFadden was hurt. He ended up rushing for 977 yards despite starting only six games, and attracted a four-year, $14 million contract from the Bears.

Forte was hurt after a third-quarter reception when Green Bay's Charles Woodson rolled up on him. He had 31 yards on seven carries before leaving. Bush managed 54 yards on 14 runs.