On Friday, Chris Mortensen of ESPN (via Adam Schefter) reported the Vikings are concerned about the ailment but still have "guarded optimism" about his status for Sunday's Week 2 game against the Pittsburgh Steelers.
However, Vikings head coach Mike Zimmer told reporters he expects Bradford to start on Sunday.
Durability has long been a concern with the Oklahoma product considering he played 10 games in 2011 and seven games in 2013. He also missed the entire 2014 campaign with a torn ACL.
However, he appeared in 15 contests for the Vikings in 2016 and finished with a career-best 3,877 passing yards to go along with 20 touchdown throws to just five interceptions. He completed 84.4 percent of his throws for 346 yards and three scores in Monday night's win over the New Orleans Saints.
While Minnesota can rely more on the rushing attack of Latavius Murray and Dalvin Cook if Bradford is out in the short term, it will likely turn to Case Keenum under center. Keenum played 10 games for the Los Angeles Rams in 2016 and finished with 2,201 passing yards, nine touchdown throws and 11 interceptions.
Keenum can keep the Vikings afloat in the short term, but they could use Bradford back and healthy as they compete for a playoff spot in the NFC North.