DETROIT -

Detroit Lions running back Reggie Bush plans to have an MRI on his left knee to determine the extent of the injury he suffered in the Lions' 25-21 loss to the Arizona Cardinals on Sunday. ESPN.com reported.

Bush's was injured when Arizona safety Tony Jefferson hit Bush's knee with his helmet after Bush made 26-yard reception in the second quarter.

Bush was cleared to return to the game. But after he fumbled in the third quarter, he left the game and did not come back in.

Bush finished the game with 25 rushing yards on nine carries and added three receptions for 44 yards.

"I was able to go back in the game, but I wasn't myself," Bush said, according to ESPN.com. "I probably shouldn't have gone back in. But I went back in and tried to give it a shot. Felt like I could still go, but I wasn't myself.

"We'll see what happens this week, I'm not sure. I don't think it's anything serious."