Not only did the Buffalo Bills get blown out Sunday but top running back Fred Jackson is out at least three weeks and receiver David Nelson is gone for the rest of the 2012 season.

An MRI exam completed on Jackson's right knee Monday revealed nothing conclusive, a source familiar with result had earlier told Schefter. It likely will be 7-10 days before a timeline is established for his return but a source estimated that the running back will miss at least a month.

Jackson went down with 11:07 left in the first half Sunday when he ran for 7 yards and was hit hard by LaRon Landry. Jackson went down immediately and stayed down for a few moments while he was checked by trainers before walking on his own to the sideline.

Jackson took to his twitter page to tell fans that he'll be back on the field as soon as possible:

"Thanks for all the prayers all well wishes. I will get back on field ASAP! Keep Billieving in us, jus more work to do!!"

Nelson, however, tore the ACL in his right knee Sunday, a league source told Schefter. Before his injury, Nelson had two catches for 31 yards Sunday. He was the team's second-leading receiver in 2011, finishing with 61 receptions for 658 yards and five touchdowns.

Both injuries are significant blows to the Bills, who entered the season with high expectations of their chances of becoming bona fide contenders.