Updated

Injured running back Jamaal Charles plans to return to Chiefs practice Sunday, though coach Andy Reid wouldn't say how much he'll participate or whether Charles will play in next weekend's preseason game at Pittsburgh.

Charles sat out Friday night's 15-13 loss to the San Francisco after straining his right foot in practice earlier in the week. The Chiefs' offense failed to score a touchdown in the game.

Charles worked out prior to kickoff, but Reid said he didn't want to risk further injury by allowing him to play in the game. Instead, Charles spent most of the night helping rookie running back Knile Davis, who got most of the reps with the No. 1 offense.