Lee, who is still recovering from a left knee injury, tweaked his right hamstring midway through practice and didn't return.
Coach Gus Bradley says ''we'll just wait and see to what degree it is and where we go from there.''
Lee, a second-round draft pick from USC in 2014, missed all organized teams activities and a three-day minicamp because of the knee injury, so the last place he wanted to be during training camp was back on the sideline.
Bradley says: ''I know for him it's disappointing. He really wanted to go. We'll get it figured out. Fortunately it's this time of year and fortunately it's not anything season-ending or anything like that. We'll deal with it.''
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