49ers look to rebound from last week's tough loss but with banged-up defense

SANTA CLARA, Calif. – The reeling San Francisco 49ers defense already had plenty to be concerned with this week before the added distraction of Aldon Smith's arrest.

First and foremost: Quarterback Andrew Luck, running back Trent Richardson and the new-look offense of the Indianapolis Colts.

The 49ers look to rebound from last week's tough loss in Seattle with a banged-up lineup.

San Francisco will be breaking in a new starting nose tackle against the Colts, has yet to gain clearance for starting rookie safety Eric Reid and has three other key starters who either missed practice or were limited this week with injuries.

But a defense that ranked third in the NFL last season is accustomed to the adversity and welcomes the challenge of a Colts backfield strengthened earlier this week when the team added Richardson via trade.