Fant was moving backward in pass protection when teammate Justin Britt, who was on the ground, rolled into him. Fant immediately went to the ground and clutched his left knee. Trainers tended to him for several minutes before carting Fant off the field.
Fant started 10 games at left tackle last year and is expected to start there again in 2017.
Pete Carroll said earlier this summer that Fant had the best offseason of any Seahawks player. Fant bulked up from 296 pounds to 320 pounds.