Chargers center Nick Hardwick, cleared by the team's medical staff and an independent doctor as part of the NFL's concussion protocol, returned to practice on Friday. Ryan Mathews (ankle) was absent from practice. He hasn't practiced this week. Last Sunday in the 27-10 playoff victory over the Bengals, Mathews didn't play after a carry early in the third quarter. Mathews suffered the left ankle injury in Game 15 against the Raiders but returned to that game and played the next two games. In the lead up to those two games, he sat out the Wednesday and Thursday practices but took part in the Friday practice, which usually is the lighter workout of the three. Mike McCoy had implied the same routine would be in place this week for Mathews. The Chargers are expected to have a light practice Saturday. They will face the Broncos on Sunday afternoon (1:40 Pacific Time) in Denver.