Fred Jackson could miss significant time with a knee injury. (Gary Wiepert/Associated Press)

Buffalo’s starting running back was drilled by LaRon Landry on the same right knee on his sixth carry of the season in Sunday’s 48-28 rout against the Jets. He did not return.

Jackson underwent an MRI Monday which was inconclusive, but ESPN’s Adam Schefter reported, citing sources, that Jackson could miss at least one month.

Update: Bills coach Chan Gailey said during his Monday press conference that Jackson will be out “a few weeks.”

And if that wasn’t bad enough, the Bills also lost wide receiver David Nelson for the season to a torn ACL.

C.J. Spiller has enough opportunity to start in Buffalo. (Mel Evans/AP)

“It’s not going to be three [weeks], but I don’t think it’s going to be eight,” Gailey said. It’s probably somewhere there in between. Hopefully sooner. The prognosis is decent.”

C.J. Spiller stepped in for Jackson and had a career day — 169 yards and a score — and has displayed the versatility to handle Jackson’s carries in his stead. But Jackson’s importance to Buffalo’s offense is impossible to ignore. His production was key during the team’s surprising 4-1 start last season, and after Jackson broke his leg Nov. 20 in Miami, the team went just 1-5.

Buffalo had hoped to split Spiller out wide as a receiver and use both backs on the field at times to provide quarterback Ryan Fitzpatrick added weapons.

Now the Bills are left with former Cowboys backup Tashard Choice as the lone man behind Spiller while Jackson is out.

Sunday’s loss was Buffalo’s sixth straight against AFC East foes, and it snuffed out much of the optimism for an already tortured fan base.

“Sunday’s 48-28 loss to the Jets didn’t feel like one game,” Buffalo News columnist Jerry Sullivan wrote. “It felt like a big, steaming pile of games, like a highlight reel of losses from the team’s recent, grisly past.”

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