EDEN PRAIRIE, Minn.  — The Minnesota Vikings face another quarterback quandary, with Sam Bradford sidelined against Tampa Bay because of an ailing left knee and Case Keenum set for his second straight start.

Vikings coach Mike Zimmer eliminated the mystery before the weekend this time.

He ruled out Bradford, who was not at practice Friday because of his injury from the season opener against New Orleans.

Bradford joined the team on the field in a limited basis Wednesday and again on Thursday, when Zimmer sounded upbeat about his progress. ESPN, citing unidentified sources, reported that Bradford was traveling to seek a second opinion from Dr. James Andrews, the noted orthopedist who performed anterior cruciate ligament reconstructions on the quarterback’s knee in 2013 and 2014.