The move was announced as the Bills' roster exemption expired for Lynch, who had completed an NFL-imposed three-game suspension for violating the league's personal-conduct policy. Lynch rejoined the team Monday, but the Bills were granted a four-day exemption to ensure he'll be ready to play Sunday, when the team travels to face the Miami Dolphins.
While Lynch was gone, the Bills' running attack didn't lose a step behind Fred Jackson, who was the offense's most valuable player through September. Jackson leads the team with 291 rushing yards and 134 receiving yards and ranks second in the NFL with 425 yards from scrimmage.
Lynch is the first to stress that he's impressed and pleased with how Jackson performed. Lynch also said he doesn't care whether he's considered Buffalo's No. 1 running back.
And yet the suspension imposed after he pleaded guilty to a misdemeanor gun charge in March gave Lynch a healthy reminder of how quickly he can be forgotten.
"It's weird," Lynch said, referring to the reaction he received from fans while he worked out in Buffalo during his suspension. "I've been hearing a lot of different mixed things like some saying, 'I can stay where I'm at, Fred's doing a wonderful job,' which I don't mind."
Lynch added that other fans couldn't wait until he returned to the team. But it wasn't until he came back to the Bills' facility -- which he had been barred from visiting during his suspension -- to rejoin his teammates when he finally felt at home.
"I'm just glad I've got these dudes on my side to let me know that I was missed," he said.
There's no question among the Bills -- particularly Jackson -- that they're ready to welcome back Lynch, who has the potential to give an inconsistent offense a necessary boost.
"Without a doubt," Jackson said. "I'm probably more excited than anybody. He's a playmaker on offense. We're looking forward to him coming in and making some plays for us."
Lynch and Jackson began providing the Bills with a one-two running punch last season, when Jackson emerged as a dependable backup in his second season with the team. Lynch and Jackson's combined 2,414 yards from scrimmage accounted for just under half of the Buffalo offense's total production.
Lynch's roster spot came at the expense of McKelvin, who was deemed expendable because there wasn't a clear timetable on when he could return after he broke his leg during the first half of last Sunday's 27-7 loss to the New Orleans Saints. McKelvin, a 2008 first-round draft pick, is the seventh Bills player to be placed on injured reserve this season.
Drayton Florence will replace McKelvin as the starter opposite Terrence McGee. A seven-year veteran who was signed in free agency this offseason, Florence had just returned last weekend after missing more than a month with a sprained knee.
Florence won't be the only new starter on a Buffalo defense that has been depleted by injuries.
Veteran backup George Wilson and 2009 second-round pick Jairus Byrd are expected to start at the safety positions in place of Donte Whitner (thumb) and Bryan Scott (high ankle sprain), who also were hurt last weekend. Starting middle linebacker Paul Posluszny is still out after breaking his left arm during the season opener at New England.
The status of starting left tackle Demetrius Bell (groin) and reserve defensive lineman John McCargo (calf) is uncertain after both missed their second consecutive practice Thursday.
Starting defensive tackle Kyle Williams practiced on a limited basis after being held out of Wednesday's session because of a groin injury. Rookie tight end Shawn Nelson returned to practice after missing last weekend's game with a strained shoulder.
The Associated Press contributed to this report.