Bradford returned from a three-game absence due to an ailing left knee in Monday's 20-17 victory over Chicago before aggravating the injury in the first half.
Should Bradford remain sidelined, Case Keenum would draw the start for the Vikings (3-2) in Sunday's home game against the NFC North rival Green Bay Packers (4-1). Keenum has four touchdown passes and no turnovers this season.
A groin injury limited Diggs to just one catch for four yards versus the Bears. The 23-year-old leads the team with 395 yards receiving and four touchdowns to go along with 23 catches.
Should Diggs sit out on Sunday, Minnesota may look to expand the workload of Michael Floyd. Floyd had a 19-yard reception in his return after a four-game suspension.