McPhee had been questionable with a knee injury. He has a team-high five sacks in his first year with Chicago.
Linebacker Shea McClellin (knee), center Hroniss Grasu (neck), running back Matt Forte (knee) and receiver Eddie Royal (knee) are inactive for the Bears. Rookie Jeremy Langford is expected to start for Forte on Monday night, and Marquess Wilson is expected to replace Royal.
The Chargers are without three-fifths of their original starting line: left tackle King Dunlap, left guard Orlando Franklin and center Chris Watt. Watt was placed on season-ending injured reserve Monday with a shoulder injury.
Safety Eric Weddle returned from a two-game layoff due to a groin injury.
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