It was another one of those days for the Vikings against the Detroit Lions. Unforced errors and uncharacteristic mistakes gave Detroit too many extra opportunities and they capitalized on them along the way to upending the Vikings 14-7 at U.S. Bank Stadium on Sunday.

Here are five takeaways from the game…

1. Cook injury, lost fumbles in 3rd quarter changed game

On consecutive plays early in the 3rd quarter, the Vikings lost fumbles and possibly their rookie running back for the season. The first lost fumble came when Jerick McKinnon took a direct snap and lost control of the football following a fake handoff to Dalvin Cook. Detroit fell on the fumble and kicked a field goal a few minutes later. On the first play of the Vikings next possession, Cook dashed through the middle of the Lions defense for a 10-yard gain before his knee buckled as he cut to avoid a tackler. Cook fell to the ground and lost possession of the ball. Detroit recovered, then scored a touchdown moments later and Cook never returned to the game. Head coach Mike Zimmer said after the game that the team is concerned about Cook's ACL. A season-ending injury is possible for Cook and that would alter the course of the Vikings offense over the final 12 games of the season, and those two lost fumbles altered the course of Sunday's game. The touchdown the Lions scored after Cook's fumble was their only touchdown of the game and it gave them a 14-7 lead (following a two-point conversion), which was also the final score of the game.

2. Lions were opportunistic, Vikings weren't

The 10 points the Lions scored off two Vikings fumbles in the 3rd quarter are examples of the Lions being opportunistic. The Vikings were unable to be as opportunistic with Detroit miscues. Three of Matthew Stafford's passes hit Vikings defenders in the hands, yet the Vikings were unable to haul any of them in for interceptions. The Vikings also missed a scoring chance when Kai Forbath's 39-yard attempt hit the right upright. It is difficult enough to win in the NFL that giving your opponent extra possessions and not capitalizing on their mistakes only makes it that much more difficult.

3. Vikings defense dominated Lions offense

It's true. The Vikings lost the game and there are issues to correct on defense, but the bottom line is the defense played lights out. They held the Lions offense to 3.7 yards per play, forced seven punts, sacked Stafford six times, held Golden Tate to 29 yards receiving and got off the field on 3rd down 10 of 13 times. Sacks were registered by Everson Griffen, Danielle Hunter (2.0), Linval Joseph, Eric Kendricks and then there was also a team sack. Aside from the six sacks, the Vikings also tallied three other tackles for loss on Lions run plays, with Griffen, Kendricks and Harrison Smith each gathering one a piece. With Sam Bradford's status up in the air and an ominous tone from Zimmer regarding Cook's prospects for the rest of the season, this type of defensive performance is encouraging and necessary for the Vikings over the final 12 games of the regular season.

4. Offensive line held its own versus tough Lions defense

The Lions defense is nothing to sneeze at. It has game-changing players at every level, including within the front seven. The Vikings offensive line held its own and at times outplayed the stout Lions defensive front. Before Cook exited the game, the Vikings were averaging 5.1 yards per carry on his touches. Also, quarterback Case Keenum was sacked just one time on the afternoon. For the most part, the blocking and protection was solid. When it wasn't, Cook evaded would-be tacklers well and Keenum found a way to buy time. With just one quarter of the season complete, there is a lot of football to be played and the Vikings offensive line looks to be one of the most improved areas of the team, something that was drastically needed and something that was a point of emphasis over the offseason.

5. No time to sulk with Bears, Packers on the horizon

The Vikings have an extra day before their next game, which is on Monday Night Football. But they have no time to sulk after a self-inflicted wound-inducing loss or feel sorry for themselves because injury might takeaway a big-time play maker. The task of playing at Soldier Field is never easy and then on a short week the following weekend the Green Bay Packers come to town. Sunday's loss to Detroit was the first of three consecutive games in 14 days against division opponents.