Answer based on context:

The 49ers played their second game of the season against the St. Louis Rams on September 17 in a Week 2 home - opener. After a loss to the Arizona Cardinals the previous week, the 49ers redeemed themselves with a win at home. Second year quarterback Alex Smith threw for 233 yards with 11 completions and one touchdown pass to Antonio Bryant. Bryant had four receptions with 131 yards. Running back Frank Gore ran for a (at the time) career-best 127 yards with a touchdown, despite Jonas Jennings and Larry Allen being sidelined with injuries. San Francisco won 20-13 and evened out their record at 1-1.

Which player missed the game due to injury?
Jonas Jennings