There was another scary moment for San Francisco 49ers rookie linebacker Reuben Foster when he left Sunday's game against the Arizona Cardinals and was being looked at by medical personnel on the sideline. Sunday was only Foster's third game of the season, and he had already left the previous two with separate injuries.

During Week 1, Foster sustained a high-ankle sprain that forced the rookie to miss the next five games. He returned for a Week 7 matchup against the Dallas Cowboys but exited with a rib injury. Foster was inactive for the 49ers' following game against the Philadelphia Eagles.

Foster was able to return and finish Sunday's game against the Cardinals, but head coach Kyle Shanahan fears that the linebacker may be hampered for the remainder of the season by the lasting effects of his Week 1 injury.

"When I looked up, I saw him make some plays," Shanahan said while speaking of Foster. "I was pretty involved with some of the situations we had on offense today so I wasn't locked into every situation we had on defense. I saw him make some plays. I thought our defense gave us a chance to win that game. I was glad Reuben was able to make it through.

"I know he went down that one time in the game. Just some lingering effects of his high-ankle sprain which I think will probably continue to bother him throughout the year, but I was glad to see him come back and finish it."

Foster finished Sunday's game with 13 total tackles, which led the defense by a significant margin.