See more of the story

CHICAGO -- The Vikings were extremely frustrated in the locker room following a 36-30 overtime loss to the Chicago Bears at Soldier Field.

Adrian Peterson, whose fumble in overtime set up Chicago's winning touchdown, was as upset as I've ever seen him. Peterson sat at his locker about 10 minutes in full uniform shaking his head. Peterson said he's never felt more disappointed after a game in his career. "I'm sick right now," he said. "I'm very disappointed. I really feel like I lost this game. We were in position to win the game and I gave it away." Peterson's fumble problems have received a lot of attention this season, but the one in overtime was easily the most costly of his career. It was his seventh fumble of the season and the sixth that he's lost. "You have to protect the ball," he said. "At the time the game is tied and I had just picked up the first down. Despite what happened in the first half and during the game, at that moment we had an opportunity to make up for that and I cut the opportunity short." The defensive players were also angry with their performance. The Vikings gave up 363 total yards, 36 points and a number of big plays to a bad Bears offense that didn't have Devin Hester. "If I could cuss right now I would," defensive end Jared Allen said. "I mean, we're playing bad right now … Each man on this team needs to go home and look himself in the mirror and figure out what we want to be this year: An 11-5 team or a 12-4 team that makes noise in the playoffs. That's just the bottom line." Monday's game was a head-spinner that featured a number of key story lines. Here are a few Wasted opportunity The Vikings' hopes of clinching the No. 1 seed in the NFC playoffs went out the window with the loss. The Saints secured home-field advantage. The Vikings and Eagles have the same record but Philadelphia owns the tiebreaker. Depending on what happens, the Vikings could end up with the No. 4 seed with a loss against the New York Giants in the regular-season finale next week. "We don't worry about nobody but this team," defensive tackle Kevin Williams said. "We can't worry about what Philly does, what New Orleans does. We have to worry about what the Vikings do. If we're not winning, none of that b.s. even matters. We have to win games and right now we've lost three out of four and that's what matters right now." Tale of two halves Players were at a loss for words to explain how the offense could look so bad in the first half and then have its way in the second half. The Vikings had only 82 yards and zero points in the first half. They finished with 30 points and 423 total yards. "I don't know how to explain it," Pro Bowl guard Steve Hutchinson said. "I don't know exactly what kickstarted it," Brett Favre said. "I think the difference, to be honest with you, we just made plays." "I don't know if it was more focus," left tackle Bryant McKinnie said. "I don't how you go from one half and then the second half you start putting up points. I can't explain it." "Night and day," Peterson said. "We really weren't moving the ball the first half. The second half we came back out and it seemed like guys woke up." Winfield struggles Pro Bowl cornerback Antoine Winfield had his second straight bad game. Winfield got beat by Devin Aromashodu on the game-winning 39-yard touchdown and he gave up a number of other plays. Winfield missed six games because of a right foot injury and it's obvious there's something wrong with him, either physically or with his timing. "Terrible," Winfield said when asked about his play. "I need to get right. I don't know what it is. I'm giving up too many big plays, missing tackles. I need to get right." Winfield said he feels 100 percent but said he's not going to make any excuses for his play the past two weeks. "I'm out there playing so I'm capable of getting my job done," he said. "I'm just not doing it right now. I did miss eight weeks, but I'm never going to use that as an excuse." On the game-winner, he said he read Bears quarterback Jay Cutler and knew a go-route was coming but he couldn't stop it. "We were in single high coverage," he said. "They knew what we were in. I knew it was a go-route. I got outside leverage and [Aromashodu] sliced inside and just took off. Good throw. Good play." Defense in tailspin The defense has major issues right now. They allowed the Bears to rush for 105 yards and Cutler to pass for 273 yards and a season-high four touchdowns. Rookie middle linebacker Jasper Brinkley had another tough outing against the Bears tight ends in coverage. Madieu Williams missed a number of plays, including failing to wrap-up on Cutler on a scramble. The list goes on and on. "Defensively, I put this all on us," Allen said. "Defensively, we did not make enough plays. We didn't tackle or stop the run like we're supposed to. It's on everybody. It's not one person or one call." Breakdown in coverage The Vikings have been pretty good covering kicks this season, but they gave up some huge returns Monday. The Bears averaged 30.6 yards on seven kickoff returns. Danieal Manning returned three kickoffs for 134 yards (44.7 yard average). The Bears average drive started at their own 44 on the seven kickoffs.