The Buffalo Bills put running back Damien Harris on injured reserve ahead of their Week 7 matchup with the New England Patriots and elevated in-demand backup RB Ty Johnson to take his place.

“The #Bills promoted RB Ty Johnson to the 53-man roster from the practice squad after the #Rams tried to sign him earlier in the week,” NFL Network insider Ian Rapoport reported on Friday. “They also placed RB Damien Harris on Injured Reserve.”

Harris is now out for at least four weeks after he left the Bills’ Week 5 win over the New York Giants in an ambulance with a neck injury. The former Patriots back was taken to a local hospital and released the next morning. Now, he won’t get a chance to play against his former team, though, this Sunday.

With Harris out, the Bills elevated Ty Johnson from the practice squad. Johnson is a fifth-year pro who has played for the Detroit Lions and New York Jets. In his previous four seasons, the former Maryland Terrapins runner has produced 208 carries for 925 yards with four rushing touchdowns and 86 catches for 668 yards with three receiving TDs.

Johnson joins James Cook and Latavius Murray in a struggling Bills backfield that hasn’t stepped up in the team’s biggest games. The team has over 100 yards rushing in all four of its wins and 97 and 29 yards rushing in its two losses.

Buffalo is a respectable 13th in the league with 709 rushing yards on the season, but only 576 of those yards are from running backs. That number would drop Buffalo to 21st in the league.

The Bills try to get their running game back on track in Week 7 against their AFC East rival Patriots at 1:00 p.m. ET.