Paul Connor faces a minimum four weeks on the sidelines after suffering suspected medial ligament damage in the 3-0 win over Darlington.
Speaking to the Lincolnshire Echo Connor said:
"It's really disappointing because I felt really good during the game against Darlington. I went in for a tackle, overstretched, and then I felt this horrible pain in my knee."
Connor stayed on the pitch for a short while afterwards, but it was clear he'd picked up an injury.
"I tried to carry on, but in the end I had to admit defeat and come off. I don't know exactly how long I am going to be out."
The news may not be what Imps fans want to hear, but one man who won't be too disappointed is Chris Fagan who looks set for a run in the first team and an opportunity to add to his two goals so far this season.