San Francisco 49ers backup quarterback C.J. Beathard suffered a foot sprain during Saturday's preseason loss to the Houston Texans. He will not practice on Tuesday, but head coach Kyle Shanahan remains hopeful he can play this Saturday against the Indianapolis Colts.

"I didn't notice it on the field but definitely saw it on the tape," Shanahan said on Sunday of the injury. "It looked pretty bad. He was walking around alright [on Sunday], but it's tough to tell with C.J. because he's so tough. But I think we'll have a better idea on Tuesday how he's moving."

Shanahan provided an update on Beathard's recovery.

"C.J.'s not practicing today," he said on Tuesday. "He definitely is trying to, but he does have a foot sprain, so we're resting him. We think it will help him for tomorrow. We'll see how he comes in tomorrow. He's day-to-day as of now."

The quarterbacks behind Beathard are Nick Mullens, who has played in each of the 49ers' first two exhibition games, and Jack Heneghan, who has not played yet.

"I would never be hesitant to play [Beathard] if he didn't practice (this week)," Shanahan continued, "but I would be if he couldn't protect himself or it could threaten him after. I want C.J. to get as many reps as we think is smart because you're hoping he doesn't get many in the season."

Shanahan also said defensive lineman Solomon Thomas and offensive lineman Garry Gilliam remain in the concussion protocol. Both sustained concussions during the 49ers' first exhibition game against the Dallas Cowboys.

"[Thomas] and Gilliam are both in the same stage," Shanahan said. "They've been cleared to have no contact, but they can go out there and do individual stuff as long as they're out of contact. If they pass that stuff today, hopefully, they can take the next step tomorrow."