The Detroit Lions’ revamped backfield has already suffered a significant setback just one week into the season.Running back Isiah Pacheco is expected to miss an extended period after undergoing surgery to remove a loose body that was pressing against a nerve in his back. The recovery could keep Pacheco sidelined for approximately 12 weeks, potentially putting an early December return in play.Lions head coach Dan Campbell stopped short of providing an exact return date but acknowledged Detroit will be without the veteran for quite some time.“It’s going to be a while,” Campbell said, describing Pacheco’s expected absence as a “significant amount of time.”Pacheco was already unavailable for the beginning of Detroit’s season. The Lions placed him on injured reserve with a designation to return on Sept. 1 after he suffered both an MCL sprain and back injury during training camp.Lions’ backfield plans take huge hit The latest development means Detroit will have to wait much longer than initially anticipated to see what Pacheco can provide alongside star running back Jahmyr Gibbs.Detroit signed Pacheco during the offseason after trading veteran David Montgomery to the Houston Texans. The move was designed to give Gibbs another proven and physical option in the backfield.Pacheco arrived in Detroit after spending his first four NFL seasons with the Kansas City Chiefs. Known for his aggressive running style, he helped Kansas City capture two Super Bowl championships before joining the Lions.With Pacheco unavailable, Gibbs becomes even more important to Detroit’s offense. He handled 29 carries in the Lions’ victory over the New Orleans Saints, demonstrating his ability to carry a heavier workload when necessary.Pacheco isn’t Detroit’s only injury concern heading into Thursday night’s matchup against the Buffalo Bills.Starting left guard Christian Mahogany suffered a hip injury against New Orleans and was carted to the locker room. Campbell indicated the injury isn’t expected to be a long-term problem, but the short week could prevent Mahogany from being ready for Buffalo.For Detroit, the immediate challenge is clear: keep the offense rolling while waiting for Pacheco to get healthy enough to make his Lions debut.More NFL news:Why Aaron Jones Sr. might not be Vikings lead RB in 2026Why Cardinals could trade Jacoby Brissett during 2026 seasonHow Travis Hunter could win Comeback Player of the Year for Jaguars in 2026Commanders’ Jayden Daniels has ‘considerable hype’ from around NFL entering 2026 seasonCowboys are ‘hoping’ to unlock George Pickens with more versatile usage