PITTSBURGH — Pittsburgh Steelers All-Pro safety Troy Polamalu injured a calf before Sunday's divisional playoff victory over San Diego and will work only lightly during the first couple of days of practice for the AFC championship game.

Polamalu wasn't introduced with the rest of the defensive starters, and coach Mike Tomlin wasn't certain if could play until Polamalu ran onto the field for the first defensive series.

Polamalu played the entire game as the Steelers won 35-24, but had no interceptions and was limited to three tackles.

The Steelers did not disclose Polamalu's injury until Tomlin's weekly news conference Tuesday.

"We're at the point of the season where it's about getting ready to play and being at the very best you can be on game day," Tomlin said Tuesday. "If that means sacrificing a little physical preparation for him, we're willing to do that."

Polamalu made the All-Pro team last week and was chosen for his fifth Pro Bowl. He tied for second in the NFL with seven interceptions.

Tomlin also said center Justin Hartwig injured a knee during the second quarter and played with a brace during the second half. Hartwig also is expected to be limited early in the practice week for Sunday night's game against AFC North rival Baltimore.