Cordarrelle Patterson arrived in Mankato three weeks ago with the same old playful smile but also a new determination to show the Vikings and a growing hoard of naysayers that a two-year-long wake-up call had been answered.

But after 90 minutes of the first practice of training camp and while making an impressive catch that showcased his still-significant athletic abilities, he suffered a shoulder injury that sidelined him for a couple of weeks.

Instead of trying to chase down passes from quarterback Teddy Bridgewater and fellow receivers Charles Johnson and Stefon Diggs on the depth chart, Patterson was stuck watching them team up for big play after big play.

“I wanted to come out here and bust my butt every day,” Patterson, a 2013 first-round draft pick, said after Tuesday’s walk-through. “I’m just ready to be out there, and when my time comes I have to make the most of it.”

His first opportunity should come Thursday night when the Vikings play the Seahawks in a preseason game at Seattle’s CenturyLink Field. Coach Mike Zimmer was noncommittal about Patterson’s status, but the expectation is he will play. Patterson, who was not ready to play against the Cincinnati Bengals in the preseason opener, knows he needs to get back on the field.

He is arguably the NFL’s top kickoff returner, having scored four touchdowns that way in three NFL seasons, so his roster spot seems secure. But to carve out a significant role on offense for the first time since the first half of the 2014 season, Patterson likely needs to show the Vikings some proof that he took seriously their requests to become a more polished pass-catcher.

Head athletic trainer Eric Sugarman tended to Cordarrelle Patterson after the receiver injured a shoulder on the first day of training camp.

If Patterson didn’t do that, Zimmer said two days after the playoff loss to the Seahawks, then he wouldn’t be anything more than a returner here.

“I’ve really kind of opened up to any challenges,” Patterson said. “Guys saying things like that … I feel like that’s a great challenge. That’s something I wanted to do every year, but I feel like [I had] just been slacking.”

So this year, in addition to the military-style conditioning work he does with trainer Frank Matrisciano in San Francisco, he did position-specific training with a private coach named Steve Calhoun. And he made sure to show up at “the Teddy Two Gloves Passing Academy” to get reps with Bridgewater.

At the end of spring workouts, Zimmer said he had seen an increased focus from Patterson and fewer of the kinds of mental mistakes, both before and after the snap, that got him benched in 2014 and kept him there in 2015.

Patterson, who scored nine touchdowns as a rookie, caught only two passes in 2015 and didn’t play a single snap on offense after Week 11. Then the Vikings used their top 2016 draft pick on wide receiver Laquon Treadwell.

“I’ve had a wake-up call these past two years,” Patterson said. “It’s been a humbling experience for me, coming off a good rookie year, getting your spot taken, then a year after that not playing. I’ve been in that fire and I feel like I’ve handled it better than anybody else could handle it.

“I’ve been humbled by it. I’ve cheered my teammates on. I haven’t been a knucklehead and gotten in trouble, not going out drinking and partying and getting in trouble with the cops. I feel like I handled it good. Some people could [let it be] their downfall and start stressing about it and saying, ‘I need to drink every day,’ and they do that and get a DUI. Or they want to smoke and get in trouble like that. That’s not something I wanted to do.”

Instead, he said he answered the wake-up call by putting in the work he hadn’t in the past and keeping a low profile other than the steady stream of social-media posts showing him training with Matrisciano or Calhoun.

But after spending more time with Bridgewater in Florida before the start of camp, Patterson hurt his left shoulder on July 29 when he crashed to the ground while making a sweet catch over cornerback Jabari Price. Patterson said he knew instantly that it was his AC joint, having suffered a similar shoulder injury in college. Thankfully, it turned out to only be a sprain.

“It hurt like crazy, but there’s nothing I can do about it but keep getting treatment on it and don’t let this shoulder slow me down,” the 6-2, 220-pound wide receiver said. “I do feel good. I’m not going to say I’m 100 percent right now. It’s at the point of time that I need to be out there.”

It is unclear how much the Vikings plan to use him as a kickoff returner in the preseason, but the possible sight of all these shorter kickoffs near the goal line, a leaguewide response to the new touchback rule (touchbacks now come to the 25-yard line), has him salivating.

The unknown with Patterson, a free agent after the season, is whether he really has turned the corner when it comes to being a wide receiver. In this offense, and with a longtime NFL coordinator in Norv Turner calling the plays, if he doesn’t run the right routes and run them sharply, he won’t play much.

He should get his first chance to show them something different in Seattle.

“I came back and I felt ready. The injury set me back a little bit. But I’m ready now,” Patterson said. “It’s been a long time coming for me and I’m just ready to get out there with my teammates and make some plays.”