Isaac Sopoaga, who has been a major cog in the 49ers' fourth-ranked run defense this season, missed practice Wednesday with what the team, on its injury report, called an infection. A source with knowledge of the situation said Sopoaga has a staph infection. It is not known where Sopoaga contracted the infection or how much time he will miss. He began feeling ill on the trip back to the Bay Area from Philadelphia.
Sopoaga and the rest of the 49ers' defensive line have stood out this season, and Sopoaga also has moonlighted in recent games as a fullback. He was in the 49ers' backfield on the game-winning drive in Philadelphia that resulted in Frank Gore's 12-yard touchdown.
If he is unable to play Sunday against the Buccaneers, third-year player Ricky Jean Francois would start in his place. That scenario also might give two undrafted rookies, Ian Williams and Demarcus Dobbs, their first action of the season. Williams likely would back up Jean Francois at nose tackle while Dobbs is in line to take the place of Will Tukuafu, who was placed on injured reserve after injuring his wrist Sunday against the Eagles.
"Both of those guys are on notice that things are changing this week," Harbaugh said of Dobbs and Williams. The two rookies have been inactive for the first four games.
Opponents are averaging only 74 rushing yards a game against the 49ers. On Sunday, they'll take on a power-running team in Tampa Bay. Its top tailback, LeGarrette Blount, ran for 82 yards in a 21-0 win over the 49ers last year. As a team, Tampa Bay racked up 162 yards on the ground in that game.
-- Matt Barrows