SANTA CLARA – Rookie linebacker Reuben Foster has made significant physical improvement just nine days after sustaining a high right ankle sprain.

The 49ers’ medical staff no longer requires Foster to wear an orthopedic boot to stabilize his foot. On Tuesday, he was seen walking briskly through the 49ers’ locker room with no hint of an issue.

Foster will not play Thursday night when the 49ers return to action against the Los Angeles Rams. Beyond this week, it remains possible Foster could make a quick return to the field.

“The one thing I know is that freak athletes tend to be freak healers, as well,” 49ers general manager John Lynch told NBC Sports Bay Area on Tuesday.

Lynch said the team will take no chances with Foster and it’s too early to tell if it’s possible he can return to the lineup Oct. 1 against the Arizona Cardinals. Foster sustained the ankle injury on the 11th play of the season opener against the Carolina Panthers.

“We think the sky’s the limit for Reuben,” Lynch said. “We just have to get him healthy and we’re going to make sure he’s all the way healthy. We can’t afford, with a guy like that, to put him out there too soon.

“He wanted to play the first week in the boot. That’s just the way he’s wired. We got to make sure he’s all the way healthy before we put him in, and we’re going to do that.”