Christian McCaffrey questionable to return with knee injury, Bills lead 14-3

49ers running back Christian McCaffrey was off to a great start in Sunday night's matchup with the Bills but had to exit the contest early in the second quarter.McCaffrey took a pitch to the right, moved slowly for a few steps, the slid to give himself up for a 5-yard loss.McCaffrey was able to go off the field under his own power, immediately making his way to the sideline medical tent. He then walked up to the locker room, according to multiple reporters on the scene.San Francisco announced McCaffrey is questionable to return with a knee injury.McCaffrey, who missed the season's first eight games with bilateral Achilles tendinitis, had rushed for 53 yards on seven carries and caught two passes for 14 yards before exiting.After McCaffrey's exit, 49ers kicker Jake Moody missed a 45-yard field goal wide left.It took just one play for the Bills to get back into the end zone, as James Cook took a run to the right 65 yards for a touchdown, giving his club a 14-3 lead.