From ESPN.com
The only downer for the Bills was the potential loss of tailback Willis McGahee, who hyperextended his right knee in the second quarter, returned briefly, and then retired to the locker room for the final 1½ quarters. Mularkey declined to elaborate on the injury, and McGahee shook off a quick inquiry about it, but the second-year tailback seems likely to miss some time. One Bills offensive veteran used the term "lost" when speaking of McGahee, and then backtracked, claiming it would not be fair to make an assessment until club officials offered a prognosis.
ESPN