Washington Redskins rookie running back Derrius Guice, who suffered a knee injury in the team’s preseason opener against the New England Patriots, has received an initial diagnosis of a sprained MCL, per Ian Rapaport of NFL Network.

Guice will undergo an MRI to confirm the diagnosis. If it is indeed an MCL sprain, it likely means that Guice will miss the rest of the preseason.

Guice, who was the team’s second-round pick, suffered the injury in the first quarter after he went down awkwardly following an impressive 34-yard run, which was subsequently called back. He had just six carries for 19 yards.

Guice’s injury is a big blow for the Redskins, who were counting on the rookie to take on a significant role in the team’s backfield this season. He has drawn rave reviews from Alex Smith during camp and was even in strong contention for the starting job. But all things considered, they are lucky it was a mere sprain and not something more serious.

The Redskins do still have a host of other options at running back that they can turn to while Guice is away. Kapri Bibbs, Samaje Perine, Rob Kelley, and Byron Marshall were also in action against the Pats, while Chris Thompson is nearing his return from a broken leg.