CHICAGO – Looks like we all spent last week asking the wrong unit about the value of starting fast.

The Vikings took Monday night's opening kickoff, moved 36 yards and used a Jeff Locke punt to pin the Bears at their 7-yard line. An OK start — Sam Bradford dropped back four times and wasn't clobbered — by a beleaguered offense handed excellent field position over to a defense that led the league in points allowed (14.0 per game) and takeaways (16).

But, three plays later, kablooey. And things stayed that way through a 20-10 loss to the Bears at Soldier Field.

Jordan Howard, a fifth-round rookie running back, took a simple handoff over left guard with 11 minutes left in the first quarter. The league's No. 3-ranked run defense (81.7 yards allowed per game) was in position to make a play.

"I should have gotten him on the ground in the hole," said free safety Harrsion Smith, who missed a tackle at the line of scrimmage. "I just didn't make the play."

Linebacker Anthony Barr was there but got single-blocked to the outside. But that wasn't as bad as what happened 8 yards upfield.

That's when seventh-round rookie strong safety Jayron Kearse looked like, well, a seventh-round draft pick who was forced into the starting lineup because of Andrew Sendejo's sprained ankle. Kearse took such a horrible angle that it got him yanked from the game immediately. He sat for a while before eventually rotating with second-year pro Anthony Harris.

Finally, 69 yards from the line of scrimmage, Howard was tackled at the Vikings 16-yard line. The Vikings went into the game having not allowed a single rusher more than 56 yards in an entire game. Howard had 71 through two carries as the Bears opened with a field goal and a 3-0 lead they never relinquished.

"That just hasn't happened to us this year," linebacker Chad Greenway said. "We're all just a little bit shocked that we didn't make that play."

You can say that again.

While the offense continued to sink, the defense finally went under as well. It gave up a season-high 403 yards, had no takeaways and had Howard bash them for 153 yards rushing and 202 total from scrimmage.

"We were terrible defensively," Smith said.

"We got outplayed," defensive end Brian Robison said.

"Last week, I said this wasn't us," said Greenway, referring to the 21-10 loss at Philadelphia. "But if you do it enough, it becomes you. That's two weeks in a row. We have to change that."

Now, the Vikings have two sides of the ball to worry about. At Philadelphia, the defense had four takeaways and was dominant.

Monday night, the Vikings gave up five plays of 20 yards or more.

Early in the second quarter, they gave up a 34-yard pass play on third-and-8. Jay Cutler sidestepped a blitzing Smith, stepped up and flipped a shovel pass to Howard as Barr closed in. That led to another Bears field goal and a 6-0 lead.

"Great play by Cutler there," Smith said. "I have to do a better job keeping my feet on that field."

On Chicago's next possession, the Bears faced third-and-9 at the Vikings 42-yard line. But, again, they converted with an 11-yard pass to Howard, who later capped the 43-yard touchdown drive with a 2-yard run to make it 13-0, Bears.

Leading 13-3, the Bears essentially clinched the game by opening the third quarter with an 11-play, 75-yard touchdown drive capped by an 11-yard pass to Alshon Jeffery.

The Bears went 3-for-3 on third downs on the drive. They converted third-and-5 with a 34-yard pass to Jeffery over Xavier Rhodes. They also converted on third-and-10 with an 11-yard pass to Jeremy Langford.

The Vikings went into the game ranked sixth in third-down defense but allowed the Bears to go 7-for-14, including 5-for-8 in the second half.

"They just seemed to have the vibe going tonight," Greenway said of the now-2-6 Bears. "I don't know why. I honestly don't know what to tell you, other than the fact it was frustrating. Yeah, brutal."

On both sides of the ball.

Mark Craig is an NFL and Vikings Insider. • Twitter: @MarkCraigNFL • E-mail: