SANTA CLARA, Calif. — Former Pro Bowl offensive tackle Marvel Smith has retired from the San Francisco 49ers after being plagued by back problems during training camp.

Smith missed practice Friday and the team announced his retirement Saturday. Coach Mike Singletary says Smith did not make the decision lightly and that the team appreciated he told them before the season started.

Smith won two Super Bowl rings with Pittsburgh and made the Pro Bowl in 2004. Smith started 108 regular-season games with Pittsburgh but only played five games last season. He had surgery on his back in November and missed the Super Bowl.

Smith signed a two-year deal with San Francisco in the offseason. He was losing his battle for the starting right tackle job to Adam Snyder.