ORCHARD PARK, N.Y. -- For the first quarter-plus Sunday night, San Francisco 49ers running back Christian McCaffrey looked poised for the breakthrough game he has been seeking since his return from an Achilles injury.
That momentum came to a screeching halt with 11:23 remaining in the second quarter against the Buffalo Bills when McCaffrey took a pitch to the right and, as he planted his feet to turn upfield, he instead opted to slide down without contact.
After the 5-yard loss, McCaffrey jumped up and quickly limped directly to the blue injury tent. After a few minutes in there, McCaffrey headed to the locker room for further examination.
Initially, McCaffrey was labeled questionable to return with a right knee injury, but he was ruled out at halftime. The 49ers would go on to lose 35-10 as the Bills clinched the AFC East.
McCaffrey will undergo an MRI on his knee Monday, ESPN's Adam Schefter reported.
McCaffrey's latest injury appeared to happen about 95 seconds before the play on which he gave himself up. With 12:58 left in the second quarter, McCaffrey burst up the middle for an 18-yard gain.
But as McCaffrey attempted to avoid the last line of Buffalo's defense, Bills safety Taylor Rapp tripped him by his right ankle, forcing McCaffrey to come down hard on his right knee.
McCaffrey checked out briefly after the play but went back in a couple of plays later for the run to the right that would ultimately end his night.
At the time of McCaffrey's injury, he had seven carries for 53 yards and two receptions for 14 yards. That included season-best rushes of 19 and 18 yards.
Sunday night was just McCaffrey's fourth game since returning from the bilateral Achilles tendinitis that kept him out for most of training camp and San Francisco's first eight games.
McCaffrey had been slowly working back into form over the past three weeks and said this week that he felt a breakout game was close.
"I feel like I'm getting a lot better," McCaffrey said Wednesday. "You have to manage your expectations a lot of times, but for me it's not about anything statistically right now. It's not about any of that stuff. It's just about getting better every single day, and I know I'm doing that, which I'm excited about."
Niners defensive tackle Kevin Givens was also ruled out with a chest injury.
