What to watch for: Chargers at Bears

A look at keys for the San Diego Chargers on Thursday night when they head to Chicago for their second game of the preseason. The game will be shown live on ESPN at 8 p.m. ET:

Stay healthy: There have been numerous injuries in the NFL this summer and arguably no team has been hit as hard as the Chargers. They have had several key players go down. San Diego did not have much depth to begin with, it cannot afford to absorb many more serious injuries. This team has been ravaged by injures the past few years, and, sadly, it seems like the Tom Telesco-Mike McCoy era is starting with the same adversity.

The receivers: With Danario Alexander and Malcom Floyd out with injuries, receivers like Vincent Brown, rookie Keenan Allen and backups Eddie Royal and Robert Meachem must step up now and show they can have a strong bond with quarterback Philip Rivers.

The running backs: Starter Ryan Mathews was solid in a cameo role last week. Versatile backup Danny Woodhead should make his debut in this game. With the receiving crew thin, the Chargers will have to show they can run the ball.

The offensive line: The first unit played well against Seattle last week and many members of the organization is confident in the group. Another strong outing against a good defense will further instill confidence in a unit that's one of the biggest concerns for the team.

Dwight Freeney: He played well last week in a limited role. Freeney put pressure on the quarterback and showed a good burst. He needs to do it again. The Chargers are depending on Freeney as the team’s best pass-rusher. Star safety Eric Weddle said opposing teams will have to game plan for the 33-year-old Freeney.