Thousands of fans flock to Mankato each summer to watch stars such as Chad Greenway, Greg Jennings and Adrian Peterson prepare for the upcoming season. But just as interesting an aspect at 2014 Verizon Vikings Training Camp will be the position battles that will unfold. Here's a sneak peek at five of them.

Starting QuarterbackTeddy Bridgewater, Matt Cassel and Christian Ponder head to Mankato with a starting job up for grabs. It's fair to look at Cassel as the starter for Day 1 of camp, but from that moment forward it's a legitimate competition. The bottom line is whoever starts for the Vikings in Week 1 against the St. Louis Rams will do so after having earned the job by winning this competition.

Bridgewater's best chance of jumping Cassel for the job is to perform consistently during drills and most of practice, but then by standing out during situations periods of practice, such as the two-minute drill, red zone and no huddle. Ponder is being given little shot by most, but he wouldn't be on the roster if the powers-that-be didn't think he could win the job.

"Christian Ponder, I know people like to beat up on him, but I've been impressed with Christian," Vikings Offensive Coordinator Norv Turner said. "With his physical ability and the way he's worked and the progress he's made. He's eliminating a lot of the negative plays."

Middle Linebacker (base defense)One of the higher-profile training camp battles this year will be that of the middle linebacker in the Vikings base defense, where Jasper Brinkley will enter camp as the likely starter but where Audie Cole and Michael Mauti will push for playing time, as well. Brinkley returns to the Vikings after one year away with the Arizona Cardinals last season, while youngsters Cole and Mauti will look to use their athleticism to impress the defensive staff.

Cornerback No. 3There's no question free agent signing Captain Munnerlyn and second-year pro Xavier Rhodes are the Vikings top two cornerbacks, but there's also no question defenses are forced to play with three-plus cornerbacks on most snaps. With that being the case, expect free agent signing Derek Cox and returning Vikings Shaun Prater, Josh Robison and Marcus Sherels to battle for the third cornerback spot.

SafetyJamarca Sanford enters camp as the incumbent starter at safety opposite Harrison Smith, but this will be another high-profile competition because returning Vikings Brandan Bishop, Robert Blanton, Mistral Raymond and Andrew Sendejo will be joined by free agent signee Kurt Coleman and draft pick Antone Exum as players with an eye on the starting job. Blanton took most of the first team reps during the offseason program while Sanford was sidelined, so he may be the main challenger but he's most certainly not the only challenger.

Offensive GuardBoth of last year's starting guards – Brandon Fusco on the right and Charlie Johnson on the left – return to 2014 Verizon Vikings Training Camp. They have shown plenty capable, as both were starters during the Vikings 10-6 playoff season in 2012. But competition is the name of the game in the NFL, and the Vikings have brought several other bodies to camp who will compete for playing time. Jeff Baca returns for his second season and veteran Joe Berger was re-signed, veteran Vladimir Ducasse was signed in free agency and rookie Austin Wentworth was signed as an undrafted free agent, and David Yankey was selected in the fifth round this past May.

Others to keep an eye on…

Backup Running Back:Matt Asiata, Joe Banyard and Dominique Williams will compete for the backup job behind Peterson, with Asiata entering camp as the favorite. But don't forget about rookie Jerick McKinnon. While he'll be behind Peterson on the depth chart, Turner will be sure to find plenty of ways to use this dynamic playmaker.

Third Tight End:Rhett Ellison and Kyle Rudolph are staples, but a third tight end may be needed in Turner's offense. Chase Ford, AC Leonard and Allen Reisner will compete for that job. Ford returns from last year's team, Leonard impressed as an undrafted free agent, and Reisner is also a familiar face who has returned to the team after a stint with the Jacksonville Jaguars.

Cornerbacks Nos. 4-6:If none of the aforementioned veterans do much to impress in Mankato, watch out for a pair of draft picks – Kendall James and Jabari Price – as well as Julian Pose or Robert Steeples to step in and grab a spot.

Reserve Defensive Tackles:Sharrif Floyd and Linval Joseph figure to start inside for the Vikings, but with Head Coach Mike Zimmer expected to employ a liberal rotation along the defensive front, reserve tackles will be in need coming out of camp. Fred Evans anchors this group, but several others can challenge for a spot.

Wide Receivers Nos. 5-6:Adam Thielen leads the way after the Vikings top four returning receivers, but a host of others are capable of making the 53-man roster with impressive training camps.