MANKATO — Scores of fans descended upon the campus of Minnesota State University, Mankato Friday for the first day of Vikings training camp no longer wondering if a certain No. 4 would appear, instead many waited to catch a glimpse of No. 28.

Finding someone wearing a No. 28 Adrian Peterson jersey wasn’t hard to accomplish, the real task might be adding up just how many Peterson jerseys littered the campus area. His jersey is the 12th-best selling in the entire league, ahead of Peyton Manning and remains the best selling among running backs in the league.

Peterson has emerged as a superstar in the NFL in his two seasons. His rare combination of speed and power make him one of the most dynamic players in the league. He owns the record for most yards rushing in a single game with 296 yards. He led the league in rushing last season with 1,760 yards and he led the NFC in rushing for the second straight season. He’s just the fourth player in NFL history to lead his league in rushing in his first two seasons.

Peterson has remained the biggest Vikings star to receive the least amount of attention the first day of training camp. Peterson graced the cover of ESPN The Magazine’s July issue and enters the season with some lofty goals once again. Among his goals: an MVP award, and rushing for 2,000 yards.

While Peterson is one of the knowns for the Vikings this season, the quarterback position continues to be in question.

As soon as Brett Favre informed the Minnesota Vikings he would remain retired the spotlight moved toward Tarvaris Jackson and Sage Rosenfels.

It’s that time of year where starting quarterback positions are up for grabs in competitions that are scrutinized down to the tiniest of details by observers and speculated over by members of the media.

At the first day of Vikings training camp Friday in Mankato the attention was squarely on Jackson and Rosenfels.

Rosenfels was an offseason acquisition, picked up in a trade with the Houston Texans. He has been a backup the majority of his career and made stops in Washington and Miami in addition to Houston. He’s started just 12 games in his career, owns a passer rating of 81.2 and has thrown 30 touchdowns and 29 interceptions.

The Vikings gave Rosenfels a two-year contract extension when he signed in March. Jackson is in the final season of his contract.

Jackson’s career stats aren’t much better. He has 20 touchdowns and 18 interceptions and a quarterback rating of 76.5, but owns a career record of 10-9.

Jackson likely has the early edge because of his familiarity with the offensive, but the two will be watched closely as training camp progresses.

“Everybody has the same plays right now; it just kind of depends where they hit on the script,” said Vikings head coach Brad Childress. “We are kind of intentional in making sure that that guy hasn’t gotten the same play twice.”

Childress said he will be looking to see if the quarterbacks are making the routine plays, hitting the proper routes and finding check downs.

“I’ve been going on four years now,” Jackson said. “I know what the coaches want out of the offense. I know exactly what I got to do as far as getting the ball to my guys.”

There will be plenty of competition in other positions during training camp and the second biggest story, with good reason, from the first day was the rookie tackle Phil Loadholt, who comes in at 6-foot-8 and is listed at 343 pounds. Comparisons between Loadholt and McKinnie, who is listed at 6-foot-8, 334 pounds, were drawn fairly quickly. Loadholt is expected to challenge Ryan Cook for the right tackle position and if he can emulate the way McKinnie has played on the left side of the line he could figure into the starting role immediately.

Loadholt acknowledged the similarity in physical stature and believes McKinnie is someone he can follow in his playing style.

“Bryant’s been doing this for a long time and he’s been real successful in this league,” Loadholt said. “It’s somebody I can definitely feed off of.”

As tumultuous as the offseason was for the team the one constant has been the defense. Things have remained quiet with the league’s best run defense — that is until Jared Allen arrives on the scene.

The gregarious Allen had plenty to say on the first day as he has grown more comfortable with the team.

“Last year I’m trying to get a feel for the defense, a feel for Pat and Kevin and Ray,” Allen said. “And now we know what’s going on. We already play off of each other.”

Allen had plenty to say about the aftermath of the Favre situation and it was clear he’s moved on.

“I’m glad everything was finished the other day,” Allen said. “This is our team. The people here in Mankato is our team. This is who we’re going with and this is who is going to win championships for us.”

As far as getting ready for the season, Allen would rather training camp be over, but he’s not ready to get to hitting just yet.

“I’m ready for training camp to be over already,” he said. “I’m not ready to hit anyone quite yet.”

Percy Harvin, the Vikings first round draft choice, was not at training camp on the first day. He and his agent are still negotiating with the team on a contract, but Childress would like to see him in camp soon.

“It’s kind of the nature of the beast with first round picks … He needs to get here as soon as he is able,” Childress said.