Team doctors examined Keller after he was seen grabbing his hamstring following a 24-yard reception from quarterback Mark Sanchez on the team's opening drive.
People point to Santonio Holmes as Sanchez's most reliable weapon, but Keller's 65 receptions led the team last season. The Jets won't take any chances putting him back on the field before the regular season.
UPDATE: More bad luck for the Jets. Reserve tight end Josh Baker went down clutching his right knee midway through the second quarter. Baker was injured attempting to haul in a Sanchez pass in Carolina's end zone. He was undercut on the play by Panthers cornerback Josh Norman. Trainers helped Baker off the field, leaving the Jets paper-thin at the position.
Follow Marc Sessler on Twitter @MarcSesslerNFL.