Steve McNair injured his right calf in Tennessee's victory over Atlanta Sunday, leaving the standout quarterback doubtful for the Titans' game this weekend against the New York Jets.
Billy Volek replaced McNair, helping rally Tennessee from a 21-point deficit for a 38-31 road victory.
Chicago also lost its starting quarterback in the second quarter, with Chris Chandler spraining his right shoulder in the Bears' 19-10 victory in Denver.
Houston quarterback David Carr missed the Texans' overtime loss to New England because of a sprained right shoulder, and Tennessee defensive end Jevon Kearse was not in uniform in Atlanta because of a sprained left ankle.
San Francisco right guard Ron Stone aggravated an injured hamstring early against the Packers and was replaced by Dwayne Ledford, who quickly sprained an ankle. The Niners also lost DT Bryant Young (knee), CB Mike Rumph (ankle) and OT Travis Kirschke (ankle) at Green Bay.
The Packers saw rookie linebacker Nick Barnett (ankle) and veteran safety Darren Sharper (ribs) get hurt, along with DT Kenny Peterson (knee) and CB Al Harris (stinger).