Gophers starting left guard Jon Christenson will be out about four weeks after having right knee surgery Monday, coach Jerry Kill said.
Christensen was injured in the first half of Saturday's 23-20 win over Colorado State and was replaced by Joe Bjorklund.
Kill said two other offensive lineman are hurt, as well, but wouldn't identify them.
"Depth is going to be tested," Gophers offensive coordinator/offensive line coach Matt Limegrover said, adding that the other dinged-up linemen will need another day or two of rest and should be ready to go for Saturday's 11 a.m. kickoff against Kent State at TCF Bank Stadium.