CHICAGO – For all the bizarre events to befall the Vikings over the past decade at Soldier Field — blown leads, obscure touchdowns and even a malfunctioning game clock — there's one school of thought that they deserve credit for escaping on Monday night with a 20-17 victory over the Bears.

It was only the Vikings' second victory at Soldier Field since 2007, and their second by three points, on a night where they pulled starting but still hobbling quarterback Sam Bradford in the second quarter, gave up a touchdown on a fake punt and were vexed at times by the mobility of Chicago rookie quarterback Mitch Trubisky, making his first NFL start. But against a Bears club that entered the night 1-3, the Vikings barely escaped because of plenty of issues of their own making.

They were penalized nine times for 69 yards and threw for an average of only 3.9 yards per pass attempt, before Harrison Smith's late interception set up the Vikings to win on a 26-yard Kai Forbath field goal in the final minute. But perhaps the most concerning development for the Vikings concerned the health of their quarterback.

After making the decision to bring Bradford back from a three-week absence against the Bears, the Vikings pulled him late in the first half, replacing him with Case Keenum after Bradford started 5-for-11 for 36 yards. The quarterback, who had missed the Vikings' past three games and wore a brace on his recuperating left knee, was sacked four times, including once for a safety, and appeared unable to move in the pocket.

Vikings coach Mike Zimmer said Bradford "aggravated his injury when he got tackled on one of the plays," but added Bradford did everything the Vikings needed him to do in practice this week and said there was no doubt he was healthy enough to play.

"He didn't want to come out," Zimmer said. "He wanted to stay in there and fight, but I didn't want to get him injured any more.

"I'm still hopeful with him," Zimmer continued. "Everything that's been said — from the medical people, the doctors, the second opinion — it's going to get better. I think he just aggravated it a little bit. We'll take it day by day and see how it goes. But I think he's going to be back and he's going to be better."

Bradford was limited during all three of the Vikings' practices this week, just as he was before the Vikings' second game against the Pittsburgh Steelers, when the team decided not to play Bradford after a pregame workout. On Monday night, Zimmer said he thought about pulling Bradford earlier, but said the quarterback "felt pretty good about things."

When the Vikings replaced Bradford with Keenum just before halftime, their offense seemed to find some life. Keenum connected on 12 of his first 13 passes for 106 yards, directing two touchdown drives as the Vikings built an eight-point lead on two different occasions.

"I think [Keenum] did well," Zimmer said. "We're not turning the ball over; we're taking good care of the football."

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The Bears had their own tricks for the Vikings. Punter Pat O'Donnell calmly tossed a pass over the middle of the Vikings defense to Benny Cunningham, who took the fake punt 38 yards for a touchdown beyond missed tackles by Marcus Sherels and Everson Griffen. And after Chicago scored a touchdown to pull within one point early in the fourth quarter, Trubisky kept the ball on a reverse option pitch to tie the score at 17-17.

The rookie's mobility was his best asset against the Vikings defense in his first career start, as the Bears implemented plenty of rollouts and bootlegs to keep the Vikings pass rush at bay. Trubisky hit 11 of his first 22 passes for 122 yards and a touchdown to Zach Miller, which came when Vikings safety Andrew Sendejo got his hand on a pass and batted it up and behind, into Miller's waiting hands.

Trubisky's youth, though, ultimately proved to be his undoing late in the fourth quarter, when he threw a pass intended for Miller despite Smith sitting just underneath the route. Six plays and 20 yards later, Forbath delivered his second field goal of the game.

On offense, McKinnon had one of his finest games in relief of injured Dalvin Cook, gaining 137 rushing and receiving yards. His 58-yard touchdown run in the third quarter was the longest carry of his career.

it tough," Zimmer said. "Defenses start loading up, and you get a chance to throw the ball some. Play-actions were better; we had a couple boot[leg]s in there that we hit for first downs. I think all those things are important. I was nervous about being able to run the football against this front, and I'm glad we were able to get some of it done."