Zimmer: Bradford aggravated knee injury in win over Bears

Minnesota Vikings head coach Mike Zimmer confirmed that Sam Bradford aggravated his knee injury in the second quarter of Monday night's win, though he is "hopeful" about the quarterback's status moving forward.

Bradford, who made his first start since Week 1, was replaced by Case Keenum for the final drive of the second quarter against the Chicago Bears.

After the game, Zimmer was clear that Bradford was healthy enough to play Monday before a second-quarter tackle re-injured his knee.

"We wouldn't have put him on the field if we felt he wasn't ready to play," Zimmer told reporters, according to Brian Murphy of the St. Paul Pioneer Press.

Zimmer did not offer a timeline for Bradford's recovery.

Bradford did not get much help from his teammates, taking four sacks before exiting the contest, which the Vikings won 20-17.