For the third straight week, the Minnesota Vikings aren't going to have quarterback Sam Bradford under center when they take the field. 

Vikings coach Mike Zimmer has announced that Bradford  (knee) won't play on Sunday against the Lions. Bradford hasn't played since Week 1, and there's still no clear indication on when he might return. 

With Bradford out, the Vikings will turn to Case Keenum for the third straight game. Although Keenum looked rusty in his first start of the season back in Week 2, a 26-9 loss to the Steelers, the Vikings backup quarterback looked like an MVP candidate during Minnesota's 34-17 win over the Buccaneers in Week 3. 

In that game, Keenum completed 25 of 33 passes for 369 yards and three touchdowns. The passing total was a career high for Keenum, who's been in the NFL since 2012. 

As for Bradford, his status remains a mystery. Although Zimmer has insisted that his quarterback is "fine," he's also said that Bradford could miss as many as six weeks.  

"He might play one game from now, he might play six weeks from now," Zimmer said on Sept. 17. "Either way, he's fine."

Three weeks after making those comments, Zimmer is still being just as vague about the health of his quarterback. 

"He's feeling better, he's just not ready to play," Zimmer said on Thursday, via the St. Paul Pioneer-Press. 

So what exactly is Bradford's status?

"Day-to-day," Zimmer said. "I don't know what day-to-day is. Day-to-day."

If he's truly day-to-day, he's been on the ugly side of day-to-day this week. He hasn't participated in a single practice. 

A possible reason that Zimmer is being so vague about Bradford's healthy status is because he actually doesn't know when his quarterback might return. Bradford's injury is apparently an odd one. After taking a low hit in Week 1, Bradford eventually underwent an MRI on his knee. However, it was apparently difficult to tell how much damage there was because Bradford had so much scar tissue in his left knee, which has been surgically repaired twice due to two separate occasions where he tore his ACL. 

Bradford hasn't been on the field since Week 1, when he threw for 346 yards and three touchdowns in a 29-19 win over the Saints.