(ALLEN PARK) – The Detroit Lions activated defensive tackle Damon Harrison off the non-football injury list before practice Thursday. The Lions had been taking things slow with Harrison in his return to the field after the big defensive tackle missed all of offseason workouts in a contract dispute. Harrison reported to the Lions for the start of training camp, but has been largely an observer during practices, working out with trainers behind closed doors. He's not expected to play in Saturday's second preseason game against the Houston Texans. Lions coach Matt Patricia says they will take things slow with Harrison and ease him into drills and practices. Harrison was arguably the Lions' most valuable defensive player last season after he came to Detroit in an October trade with the New York Giants. He had 50 tackles and a career-high 3.5 sacks in 10 games, and was the key to the Lions' second-half defensive turnaround. The Lions allowed six points fewer per game with Harrison in the lineup than they did before he arrived, and gave up 57 fewer rushing yards per game. Harrison, who has two years left on a contract that's scheduled to pay him $6.75 million this fall, still could see a contract adjustment before the start of the season, though the Lions have declined to talk publicly about his deal.