It's unclear when Whitehead was injured, but it was announced he would be out for the game prior to the second half of the Patriots' 30-28 victory.
Lions coach Jim Caldwell didn't have much update on the injury after the game, saying Whitehead would have more information on Saturday.
Whitehead, however, tweeted Saturday morning to a concerned fan that "all is well."
All is well boss. ✊🏾🙏🏾 preciate the concern. https://t.co/vYy2ObEPEy— Tahir Whitehead (@Big_Tah47) August 26, 2017
Whitehead, the franchise's middle linebacker and leading tackler last season with 132 stops, moved to outside linebacker this season after the team drafted Jarrad Davis in the first round. He was expected to be the team's No. 2 linebacker and a three-down player this season.
Whitehead had been dealing with a knee injury that held him out of workouts during the spring, according to the Detroit Free Press.
Lions tight end Cole Wick was also ruled out after suffering a chest injury in the first half.
Also, running back Zach Zenner was held out of Friday's game after tweaking a muscle during warmups. According to a source, sitting him was precautionary and it is not believed to be serious.