The most significant part of the Minnesota Vikings' offseason program begins May 26, when the team will hold 10 organized team activities and a three-day mandatory minicamp in a four-week stretch. Before that begins, we're taking a position-by-position look at the Vikings' roster, and some key battles to watch:
Position: Offensive line
Who's new: The Vikings used three of their 10 draft choices on offensive linemen -- tackles T.J. Clemmings, Tyrus Thompson and Austin Shepherd -- and added two more (center Tom Farniok and guard Bobby Vardaro) as undrafted free agents.
1. Matt Kalil: He had a pair of knee surgeries this offseason, and the Vikings believe his struggles of 2014 are a thing of the past. If Kalil gets more help from the Vikings' new left guard than he got from Charlie Johnson last season, it'll go a long way toward getting him back on track.
2. Carter Bykowski: He'll probably have to battle for a roster spot in the end, considering the Vikings won't keep a backup at each position, but the Eden Prairie, Minnesota, native will get a shot after joining the team late last season.
1. Joe Berger: There's one starting position up for grabs on the Vikings' offensive line, and Berger will get the first chance at it after the Vikings brought him back on a two-year deal this offseason.
2. David Yankey: The Vikings are pleased with how he's looked this spring, and while he's not assured to be ahead of rookies such as Thompson and Hastings, he's certainly got a better chance than he did at this time last year.
1. John Sullivan: The Vikings gave him a contract extension this offseason to ensure he's there for Teddy Bridgewater's future. Mobile, intelligent and resourceful, he's a key piece of the QB's support system.
2. Berger: If he doesn't win the starting left guard job, he's the backup for Sullivan. Farniok and second-year man Zac Kerin will try to make an impression this spring.
1. Brandon Fusco: He should be back from a torn pectoral muscle, and the Vikings are certainly happy to see him return. He might be the team's best run blocker, and it was clear the Vikings had big plans for him as a pulling guard before he got hurt last season.
2. Shepherd: The Vikings will look at him at guard after he played tackle in college, and he'll have to develop a stronger lower body to play guard in the NFL. He comes in with a reputation as a smart and tenacious player, though.
1. Phil Loadholt: This is an important year for the 29-year-old, who is returning from a torn pectoral muscle and entering the third year of a four-year deal. If he and Fusco are once again blocking for Adrian Peterson, the Vikings will have the power train of their running game back on line.
2. Clemmings: He could eventually end up at guard or as a starter at one of the tackle positions. The Vikings believe they got a steal in the fourth round, though, and they're confident Clemmings' foot injury is nothing to worry about.
Position battles to watch: The left guard spot is the main battle, as Berger competes with a couple of younger players, but the Vikings have enough flexibility with their backup spots that the rest of the group could take on a number of different forms. Mike Harris returns as a swing tackle option who can also play guard, and the Vikings are optimistic about the potential of Babatunde Aiyegbusi, the 6-foot-9 Polish tackle they signed this spring. We know who most of the starters will be, but the Vikings have plenty to decide on the line over the next few months.