The NFL’s Defensive Rookie of the Month for October has found November to be more difficult.

Vikings middle linebacker Eric Kendricks suffered a rib injury Nov. 1 at Chicago and sat out Sunday’s 21-18 win over St. Louis at TCF Bank Stadium. He said Monday he’s feeling better but wouldn’t speculate on whether he will be able to return Sunday at Oakland.

“I’m still taking it day by day,” Kendricks said. “I’m doing my best to get better. I’m in treatment every day, and that’s all I can say.

“I’m listening to my body at this point.”

Kendricks wouldn’t discuss the specifics of his injury, including whether he suffered a broken rib. Vikings coach Mike Zimmer said he doesn’t know if Kendricks will be able to play against the Raiders.

“I think he’s feeling better, but we’ll just see as the week goes on,” he said.

Kendricks was replaced Sunday by Audie Cole, who suffered a season-ending fractured right ankle midway through the fourth quarter. He’s expected to be placed on injured reserve.

Minnesota could use the roster spot to activate cornerback Josh Robinson, who is on the physically unable to perform list while recovering from a partially torn pectoral muscle but returned to practice three weeks ago. The Vikings must decide this week whether to restore Robinson to the roster or lose him for the rest of the season.

While the Vikings’ depth at linebacker will be tested, at least Anthony Barr’s left arm injury is apparently not serious. After Sunday’s game, Barr had his left arm in a cast and said he would get X-rays.

Zimmer confirmed Monday that Barr had X-rays but said he “should be fine.”

Veteran linebacker Chad Greenway, whose snaps have been reduced this season, was in for all 74 defensive plays against the Rams and tied for the team lead with 10 tackles.

Greenway started the game on the outside and moved to the middle when Cole was hurt. Second-year man Brandon Watts replaced him on the outside.

“I told (Greenway) during the week, ‘Hey, you might have to play the whole game. Can you handle this or not?’ ” Zimmer said. “I thought he played well.”

Also injured Sunday was cornerback Terence Newman, who was kicked in the head by running back Todd Gurley in the third quarter and diagnosed with a concussion. Zimmer said Monday he passed the first test of the NFL’s mandated protocol.