 -- EDEN PRAIRIE, Minn. -- Minnesota Vikings quarterback Sam Bradford says the injury he sustained to his left knee during Week 1 was not the result of contact.

"I felt it when it happened," Bradford said. "I honestly didn't think it was that big of a deal, and then the longer the game went on, it started to feel just a little bit worse and a little worse. Woke up Tuesday, and it just didn't feel very good."

Bradford said he has a clear indication of what the injury diagnosis is, but he would not elaborate on the severity.

Bradford was limited in practice last week and was made inactive during Minnesota's 26-9 loss at Pittsburgh after going through a light pregame workout where he was trying to determine how his knee would respond to playing in a game.

"Really just trying to figure out if I could move, what my limitations were, if I was going to be able to go out there and do what I needed to be able to play quarterback and make moves and protect myself," he said. "I was hoping that it was going to feel better than it did having rested it on Saturday without really doing a whole lot. Sunday it just didn't feel right. It wasn't ready to go."

Vikings coach Mike Zimmer said Bradford remains day-to-day, and the plan is for him to go through practice on Wednesday with the chances of him starting on Sunday still undetermined.

"I would like to think that they're good, but I think a lot of it just depends on how my knee responds when we go out there in practice this week," Bradford said of possibly being ready to play on Sunday. "Hopefully it will continue to get better, but I think a large part of that is depending on how it responds."

Bradford tore the ACL in his left knee in 2013 and again in 2014. He underwent surgeries to repair the ligament and has experience with what has worked and what hasn't with his rehab. But, as Bradford revealed, the quarterback is in unfamiliar territory with the injury he sustained on Sept. 11.

"This particular issue we're dealing with, I'm not sure if I've ever dealt with it before," he said.

Bradford wouldn't disclose what kind of treatment he's undergoing to reduce the swelling in his knee or whether he had received a cortisone shot.

"We've done a lot of work over the past week trying to make sure that the swelling is out of there, trying to get that controlled and just trying to get it to feel as good as it can," he said.

Whether this will be a chronic issue remains in question.

"I think we'll figure that out as we go," he said. "Hopefully it'll continue to get better each day and we'll look back in a few days or whenever that time is and hopefully it's something we're not having to deal with again. If it is something that lingers and we have to deal with it, then we'll figure out the best approach on how to manage it."