Polamalu first injured his calf against the Denver Broncos in Week 1 and subsequently missed Pittsburgh's Week 2 and Week 3 contests. After a week of recovery during the Steelers' bye week, Polamalu finally returned to action Sunday. However, he was only able to stay on the field for one quarter before exiting.
Polamalu has already been ruled out for Pittsburgh's Thursday night matchup with the Tennessee Titans.
LaMarr Woodley also left Sunday's game for the Steelers. In the second quarter, Woodley injured his hamstring. He did not return to the game, and it is unlikely he will play Thursday night.
The injuries to Polamalu and Woodley weaken a Pittsburgh Steelers defense that ranks in the top five of the NFL, with only 280 yards allowed per game.