The Bills not only got blown out Sunday but top RB Fred Jackson is out at least 3 weeks and receiver David Nelson is gone for the rest of the 2012 season.

Coach Chan Gailey gave the injury updates at his weekly meeting, confirming an earlier report.

An MRI exam finished on Jackson’s right knee disclosed nothing definitive, a source conversant with result had earlier related. It likely will be 7-10 days before a timeline is established for his return but a source estimated that the RB will miss at least a month.

Nelson, in the meantime, tore the ACL in his right knee Sunday, a league source asserted. Before his injury, Nelson had 2 catches for 31 yards Sunday. He was the team’s 2nd-leading receiver in 2011, finishing with 61 receptions for 658 yards and 5 touchdowns.

Both players were hurt in the Bills’ 48-28 Week 1 blowout loss to the N.Y Jets.

Jackson, who went on injured reserve, last November with a broken right leg, 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 right away and stayed down for a few moments while he was checked by trainers before walking on his very own to the sideline.

C.J. Spiller replaced him and got the Buffalo Bills on the scoreboard, zipping past a few missed tackles by Landry and Bart Scott and scooting into the end zone for a career-best 56-yard score. Spiller finished with a career-best 169 yards rushing.

Nelson was hurt early into the 4th quarter when he went down away from the play. After being helped off the field, he was spotted walking on the injured leg along the sideline.

Jackson finished 2011 with 934 yards and 6 touchdowns. He has rushed for a minimum of 9 hundred yards in each of the last 3 seasons, including 2009 when he had a career-best 1,062 rushing yards.

Both wounds are major blows to the Bills, who entered the season with high expectations of their chances of becoming real contenders. Sports scores

Jackson was expected to provide Buffalo’s running attack a considerable 1-2 punch along with Spiller. Now, Buffalo is suddenly thin at the RB position, with Tashard Choice serving as the lone backup.

The Buffalo Bills do have 2 fullbacks in Corey McIntyre, whose mostly been employed as a blocker, and Dorin Dickerson, who is anticipated to be used in the passing game.

The depth is no better at receiver as a result of Nelson’s injury.

In opening the season with 6 receivers, including Brad Smith, who doubles as the team’s wildcat QB, the Bills were already thin and limping at the position to begin with.

Starter Stevie Johnson had four catches for 55 yards and a touchdown against the Jets despite being hampered by a groin injury which has nagged him for a lot of the offseason. And there are concerns that Johnson will have to continue playing thru the pain for the remainder of this year.