EARTH CITY, Mo. -- St. Louis Rams quarterback Case Keenum has still not made it through the concussion protocol and will be questionable for this Sunday's game against the Cincinnati Bengals.

While Rams coach Jeff Fisher expressed some optimism that Keenum could show improvement Saturday and still start, almost all signs point to Nick Foles returning to the starting job this week.

“At this point, Case has been limited in practice," Fisher said. "Unless we get good news tomorrow, then Nick will be our starter. If he’s completely cleared and he feels good, then [Keenum will] start. But, as it is right now, it’s looking like we’re going to potentially have to go with Nick, which is great. I’m so excited about Nick getting a chance to play. Then, Case might be our third, unless things get better tomorrow.”

Under league rules, Keenum has been able to participate in practice this week on a limited basis as he recovers from the concussion he suffered on Sunday. For most of the week, Keenum split reps in practice with Foles, but Foles took more than Keenum on Friday as the Rams finished practice outside in the rain.

The Rams benched Foles after their 37-13 loss to Chicago on Nov. 15. At the time, Fisher said that he hoped Keenum could provide a spark to the offense and that Foles needed to take a breather and step back for a bit.

“I’m always ready, so whenever that number’s called I stay ready," Foles said Friday. "It’s not like I turn it on or turn it off. I just stay ready. If that’s what they want to do, I’m going to be the same Nick and hopefully just play better. You want to go in there and play better, get a win, play efficient on offense and get drives going. That’s the goal.”

Fisher said there are some more tests for Keenum to clear the concussion protocol and those will be administered on Saturday. But it still seems unlikely that the Rams will rush Keenum back into the mix after the circumstances surrounding his concussion and the fallout afterward.

"There will be some more tests that are done tomorrow," Fisher said. "We’re not going to subject him to any risk whatsoever.”

If Keenum is unable to start, the Rams will likely use rookie Sean Mannion as Foles' backup. Fisher said Foles is ready to go if called upon.

“He had a great week," Fisher said. "He seized the opportunity and he had a great week this week. So, he loves the game plan and he’s ready to play. I think our offense understands where the challenges are and we need to score points. Nick’s excited about the opportunity if he plays.”