The Detroit Lions have confirmed that first-round Draft pick Ezekiel Ansah suffered a concussion during a practice last month.
The defensive end has not practised since sustaining the head injury on August 24.
The 24-year-old took part in a solo workout yesterday as he works towards passing the league's protocol for returning from a concussion.
The Ghanaian made 62 tackles, 4.5 sacks, an interception and a forced fumble during his final year in college.