EAGAN, Minn. -- Late on the morning of June 6, Byron Murphy Jr. looked across the line of scrimmage. The Minnesota Vikings' newest cornerback took immediate measure of the player he was about to spend the next three months competing against.

Justin Jefferson, the reigning NFL Offensive Player of the Year, looked back at Murphy. And it was on.

"Right away I was like, 'Oh man, he really is different," Murphy recalled recently. "There's a reason why he is a 99 overall [on EA Madden]. I just started telling people that going against him is going to get me better every single day."

From that initial day of minicamp until the end of August, Murphy and Jefferson waged a friendly, competitive and productive battle that portended everything the Vikings hope to be in 2023. Jefferson won his share of matchups, as expected, but Murphy held his own on others and earned enough respect from Jefferson that he excitedly told quarterback Kirk Cousins about it during a training camp conversation.

"We said it at the beginning of us going up against each other," Jefferson said. "He's learning from me and I'm learning from him. I'm going to get him better and he's going to get me better. Just every single day having that competitiveness in both of us, to want to make each other better. Of course he wants to lock me down. Of course I want to make plays on him. And that's what's going to get us better on Sundays. I'm always going to be that type of guy to always push my teammate to do better and to be better."

Their summer battles appeared to pay off in Week 1 even as the Vikings lost, 20-17, to the Tampa Bay Buccaneers. Jefferson caught nine passes for 150 yards, setting an NFL record for most 150-yard games before the age of 25. Murphy, meanwhile, helped limit Buccaneers slot receivers to 22 yards, a subsection of their defense the Vikings aimed to improve by signing him to a two-year free agent contract worth $17.5 million. Their presence will be essential to any chance the team has to win Thursday night against the Philadelphia Eagles (8:15 p.m. ET, Prime Video).

"We call it interactive learning," said Daronte Jones, the Vikings' defensive pass game coordinator. "And that's what Murph was getting all camp."

JEFFERSON HAD SKIPPED the voluntary portion of the Vikings' offseason program, but he participated in their two-day June minicamp and then came in hot for training camp. The backdrop was clear. Jefferson was deep in negotiations that he hoped would lead to a record-setting contract extension. As teammates Danielle Hunter and T.J. Hockenson used their participation in training camp as leverage to extract new deals, Jefferson pursued the opposite approach.

As far as anyone could tell, Jefferson did not take off so much as a single rep during the entire duration of camp, even after a season in which he had secured unanimous All-Pro honors and the NFL's Offensive Player of the Year award. He unleashed his full repertoire on the Vikings' defense, and it was intense. Into that cauldron stepped Murphy, who was already feeling pressure to prove himself after moving to a new team.

"Part of myself and me overall is that I want to show everybody I'm the best, and that I know I am," Murphy said. "But then you go to practice and play against a guy like that, and you have to realize he's going to make you better every single day."

"Of course @byronmurphy! He said it at the beginning of us going against each other. He's learning from me and I'm learning from him. I'm going to get him better and he's going to get me better." WR Justin Jefferson on who's impressed him the most in the DB room. pic.twitter.com/AnwMGPrRcw

— Minnesota Vikings (@Vikings) August 23, 2023

The Vikings had jettisoned their top five cornerbacks from 2022 and acquired Murphy with a specific if unusual plan. They viewed him as a hybrid upgrade to their 2022 nickel cornerback, Chandon Sullivan, who allowed an NFL-high 502 passing yards as the nearest defender when lined up in the slot at the start of a play, according to NFL Next Gen Stats.

Murphy would start at cornerback when the team was in its base defense but would move inside to cover the slot receiver when they shifted to certain nickel packages. That arrangement sometimes prevented Murphy from matching up with Jefferson during camp drills, but Murphy said he took every opportunity he could to arrange the positional lines to maximize their reps.

Jefferson took notice amid the sea of new faces at the position.

"I asked Justin his thoughts on our DBs," Cousins said, "and the first name he mentioned was Byron Murphy. Very complimentary. I think he has done a great job. He's a very natural nickel, which is a very important position more and more in this league."

At Jefferson's behest, the pair focused on one part of route running and defending: patience. For Jefferson, that meant waiting longer to declare his ultimate direction at the top of his route.

"I could see that if he was going to go inside, he was staying more outside before he would go back in," Murphy said. "That's what he was doing in practice. He knew that if I commit to something he's doing, it's going to allow him to either play toward that technique or away from it. So he did a really good job of knowing that, and slowing down his game in that moment, just perfecting his craft at the top of the route."

The work reminded Jefferson of his practice efforts to get free agent veteran cornerback Patrick Peterson, who spent two seasons with the Vikings before signing with the Pittsburgh Steelers last spring.

"Just like I try to have patience in my routes," Jefferson said, "[Murphy] tries to have patience with his steps as well. [Peterson] was very patient with his steps. He wasn't going for every single head move and every single step. He was patient in his technique, knowing his leverages, and I see the same thing in Byron. He's definitely a great competitor. Of course he's definitely athletic, and it's tough to make those cuts on him and get past him."

In what proved to be a revealing climax to training camp, Murphy put on a show in a pair of joint practices with the Arizona Cardinals, his former team. After spending the summer chasing Jefferson, Murphy blanketed Cardinals receivers. The Vikings splashed two of his interceptions on social media

"I definitely think working against him helped me that week," Murphy said. "He makes me work on my technique and it was like, 'OK, this is what I've been working on, and this is the type of receiver I'm working with, so let's bring that to the next person.'"

As he headed into the season, Murphy was asked what type of player he thought he had become.

"I think this year is going to be a dominant year for me overall," he said. "In every aspect."

IT'S EASY TO fall back on sports clichés, and the term "iron sharpens iron" came up a few times in relation to the work between Jefferson and Murphy. But Jefferson's impact on Murphy, and the Vikings' defense as a whole, is no comparison to how he will influence their offense, the outcome of their games and the ultimate direction of their franchise. So it was instructive to watch Jefferson's emotions run hot during Sunday's loss, one that came a day after he and the Vikings broke off contract talks amid plans to revisit them after the season.

After a second-quarter interception, Jefferson hit Buccaneers safety Christian Izien so hard that his own helmet flew off. When he tripped on a final move at the end of a 42-yard catch-and-run in the second quarter, he thumped his thigh pads three times in rapid succession. And after the Buccaneers closed out the game by converting a pair of third downs on their final possession, Jefferson sat alone on the Vikings' bench. He was one of their last players to head into the locker room.

Afterward, Jefferson said he was "moving on" from the disappointing outcome of his contract talks. When asked if his view of the franchise had changed, he said "not really" and added that his mindset wouldn't change.

Jefferson had signaled that he was seeking a contract unlike any other signed by a wide receiver. Two days before negotiations ended, Jefferson said there was no current or former player he could seek advice from.

"I've done something that no one has ever done in the history of the game," he said at the time. "So my situation is a little bit different than everyone else's."

For the time being, at least, the only advice Jefferson can follow is a missive that Cousins delivered this summer. When asked about Jefferson's determination to improve his technique during camp battles with Murphy, Cousins said he had recently sent Jefferson and fellow receiver K.J. Osborn video of a 30-minute interview that Hall of Fame receiver Jerry Rice once gave about elite-level play.

The interview detailed Rice's "borderline paranoia to get better," Cousins said.

Describing his message to Jefferson, Cousins said: "Great, you had a great [three]-year run. Pro Bowl, All-Pro. Great, you're the second-best player in the league according to the NFL Network. That's all great. Can you do it for double-digit years? That will always be my challenge to Justin, and he knows that, and that's why he has that approach of, how do I get better? How do I improve?...

"Because there are too many players I've watched in my 12 years who've had a nice run and it ended way too fast. And I'm saying to Justin, 'Don't let that be you.'"