SANTA CLARA, Calif. (AP) - Demarcus Dobbs' season is over with the San Francisco 49ers after he was placed on injured reserve Tuesday with a right knee problem.

Dobbs was injured when he landed awkwardly in the first half of Sunday's 27-13 victory against the Miami Dolphins and he had to be carted off the field before halftime. Coach Jim Harbaugh had remained optimistic in Dobbs' case, though the coach cautioned he wouldn't know anything until MRI results came back.

Dobbs returned to the field Sunday after he didn't travel for the game at St. Louis on Dec. 2 following his arrest Nov. 30 - his 25th birthday - for suspicion of driving under the influence and possession of marijuana. Dobbs expressed afterward how sorry he was and also fortunate considering the situation in Dallas.

The second-year pro had seven tackles in 12 games this year.