The Vikings are counting on Adrian Peterson's bruised calf holding up for four quarters and helping the team avoid falling to 0-4 for the fourth time in franchise history when it travels to Kansas City on Sunday.Peterson missed practice on Wednesday and was limited on Thursday. But neither he, nor coach Leslie Frazier are concerned about the injury affecting Peterson on Sunday at Arrowhead Stadium.It's sore, but it's not really bothering me, Peterson said. With a contusion, it's all about trying to flush it out and keep the muscle loose. I have a high tolerance for pain. Pain is only temporary. ... I'll be ready to roll on Sunday.Peterson said he was kneed in the calf right before halftime of last week's 26-23 overtime loss to the Lions. He said the calf didn't stiffen up until after the game, so it played no role in him only getting five carries for five yards in the second half.Peterson's second-half carries have been a hot topic in Minnesota this week. He's carried the ball only 22 times for 66 yards (3.0 average) in the second half as the Vikings have blown halftime leads of 10, 17 and 20 points.Offensive coordinator Bill Musgrave echoed Frazier's comments earlier this week, saying the coaches need to stay committed to giving the ball to Peterson.We just need to do better, Musgrave said. And obviously the last three games, what we've been doing in the second half is not good enough, in any respect. We look forward to getting that corrected.--The Vikings aren't panicking, but they're definitely concerned about quarterback Donovan McNabb's accuracy or, more specifically, his lack thereof.Offensive coordinator Bill Musgrave and quarterbacks coach Craig Johnson spent Monday and Tuesday reviewing film of McNabb and trying to figure out what can be done with his mechanics and fundamentals to help him improve on a completion percentage that's stuck at 58.0 heading into Sunday's game at Kansas City.Coach Leslie Frazier said it's standard procedure for coaches of all positions to analyze their players' mechanics and look for ways to improve. And that even goes for 34-year-old quarterbacks who have been in the league for 13 years.It's not a whole lot different than a guy who's a Cy Young Official Jason Campbell Jersey winner in baseball, Frazier said. You're always trying to improve on what you have. You don't want to ever stay the same. I just know from experience that if you can continue to work on technique, whether you're a 10-year vet, Permier Jason Campbell Jersey an 11-year vet you want to always watch tape and try to improve on technique and fundamentals.If you ever get to the point where you think you are perfect, that's exactly when you'll see things start to get out of whack.Speaking of out of whack, the Vikings are 0-3 despite having trailed for only 6 minutes, 51 seconds this season. They've blown halftime leads of 10, 17 and 20 points while being outscored 67-6. But while the defense isn't innocent, it's the offense's inability to make plays and stay on the field that has started the collapses each week.McNabb has led the Vikings to only two field goals in 16 second-half possessions. He's got a league-low 37.5 completion percentage on third downs. He's also completed just 1 of 11 passes for eight yards and no first downs on third downs in the Authentic Jason Campbell Jersey Black second half.Frazier said the points of emphasis with McNabb in Replica Jason Campbell Jersey practice this week include footwook, launch points and drops.McNabb said he self-evaluates weekly and is OK with the coaches offering input on what he can do to improve. But when asked if he needs to change anything, McNabb simply said, No.I think the thing about it is when you're critical of yourself and your play, you just look at your reads, how fast you get the ball out, obviously footwork and everything, McNabb said. But that's not just my position. That's everyone. As a quarterback, when you're watching yourself, it's everything. It's not just mechanics. It's ball placement, it's the right read and things of that nature. That's kind of how I evaluate myself each and every week as I'm watching.McNabb said some of this off-target throws have come because he's anticipating throws. He still doesn't have his timing down with the receivers in this new offense, and he's also dealt with a lot of pressure from the pass rush.Sometimes you anticipate throws, Louis Murphy Authentic Jersey McNabb said. If you have pressure in your face or whatever it may be, you try to anticipate throws, especially against man coverage. You want to have the ball cheap nfl jerseys china out before the DB even turns his head around to give your guys an opportunity. Some throws you just miss.Again, for me it's just evaluating myself and watching each and every week, if it's overstriding on the throw, trying to put it outside when the receiver is taking a step inside, whatever it may be. Those things have to be corrected and I look forward to it being corrected.It certainly Jason Campbell Jersey Black would go a long way toward helping him end his 1-8 slide as a starter in his last nine games.SERIES HISTORY Jason Campbell Jersey White 10th regular-season meeting. Chiefs lead series, 5-4. Kansas City is 3-1 at home. Most historic meeting between the teams was in Super Bowl IV, when the Chiefs beat the Vikings 23-7 in New Orleans.Copyright (C) 2011 The Authentic Louis Murphy Jersey Sports Xchange. All Rights Reserved.