IRVING, Texas — As the Dallas Cowboys (6-2) prepare for Sunday’s showdown with the Arizona Cardinals (6-1) at AT&T Stadium, they are doing so with an uncertain status for quarterback Tony Romo.

Romo sustained a severe back contusion Monday in Dallas’ 20-17 overtime loss to the Washington Redskins. Though X-rays and a CT scan were negative for a skeletal injury or anything related to the back surgery he underwent last December to repair a herniated disk, Romo is not likely to practice this week. There is no guarantee he will play Sunday against the Cardinals.

His status has everything to do with pain tolerance and an ability to function in the game. Romo took an injection to return to the game Monday, but the soreness and pain remain severe. The doctors hope it will subside before the end of the week so they can make a better determination about his status.

It likely will come down to a game-time decision Sunday.

“I’m just taking it day by day,” Romo said Wednesday. “Went and got a CT scan and talked to doc and went through all the stuff you’ve got to go through. Just take it day by day. I don’t want to get into specifics about what it is. We’ve already looked at it. It will be something you’ll look at each day. It’s unrelated to (anything) previous. You’ve got to figure out a way to manage it and go from there.”

Cowboys owner Jerry Jones said, “At this time, we have nothing medically that would prevent him from playing. What I mean by that is that there’s nothing to his injury that technically won’t function. This is a function of pain tolerance. But it’s a serious issue that you could look at. People that have had a similar type injury and they haven’t played the next week, so that would cause you some concern about him playing.

“It is not, at this juncture, in any way, a season-ending injury. But it is one that raises the question of whether or not he can tolerate a certain amount of pain in that area. That’s about what we know right now.”

Romo played through painful injuries many times in the past, including in 2011, when he came back from a punctured lung to lead the Cowboys to victory over the San Francisco 49ers. He played through severe pain in his legs and back caused by of a herniated disk to direct a comeback victory against the Washington Redskins last December.

The decision will be based on his ability to function and do all the things necessary to succeed at quarterback.

“If it turns out to be just a pain tolerance, I will play,” Romo said. “That part has never been an issue. But we got to wait and see. It will be about your ability to be productive in some fashion. That part of it we will continue to evaluate.”

Cowboys coach Jason Garrett called Romo’s status day-to-day.

“We’ll see how he handles the pain and we’ll see how functional he is as the week goes on to see what his availability is for this ballgame,” Garrett said.

Being able to function is important against a blitz-happy Arizona defense that likely will dial up even more pressure after watching the Cowboys struggle against the Redskins’ blitz.

Romo was sacked five times as the Cowboys had trouble accounting for the additional rushers.

“(The Redskins) did a couple things that were a little different that we had some miscommunication on,” Romo said. “We will be a lot more ready in the future if we see things like that. I think you have to give them credit; they did a good job. A couple of situations kind of fell into a couple of things. They had (more) people coming than we had blockers. You can have things to adapt to that, and we will adjust to it going forward.”