San Francisco 49ers right tackle Jonas Jennings and cornerback Shawntae Spencer are expected to miss Sunday's game against the Detroit Lions after getting injured last week.

Jennings, who committed three penalties in the first half in Seattle, has a shoulder injury, while Spencer has a knee problem.

Coach Mike Nolan wouldn't say who will replace Spencer as the 49ers' third cornerback, but veteran Barry Sims will replace Jennings.