Nick Saban took the time Saturday after practice to talk about some injuries and one of them was to former five-star and the top overall recruit in 2017, Najee Harris. Coach Saban said (via 247Sports) that he suffered a pulled muscle, but does expect him back in practice on Monday.
Harris is supposed to see the field as a true freshman despite Damien Harris and Bo Scarbrough returning for their junior seasons. However, missing time on the practice field could hurt him even if it does turn out to be only one practice. He's got to see every touch possible if he wants to supplant either of those upperclassmen.
The younger Harris has everything Saban likes in a running back though as he's got pure power and is quite speedy for a guy who stands 6'2" and about 227 pounds. This could be an injury that will need some monitoring as nagging pulled muscles could be a severe issue down the road.