Husker junior defensive end Randy Gregory left the game in the first quarter and didn't return to action, coming to the field in street clothes for the beginning of the second half of Nebraska's 55-7 season-opening win over Florida Atlantic.
Gregory had a slight limp as he walked along the sidelines to test things out in between trainers examining his left leg.
Nebraska head coach Bo Pelini didn't specify the injury, but said: "We'll find out. He probably could have went back in the game but we decided not to. It's probably day to day. It's hard to say right now."
With Gregory out, walk-on junior Jack Gangwish saw the majority of snaps at the end spot opposite Greg McMullen.