Cardinals wide receiver J.J. Nelson hauls in a 57-yard catch from Carson Palmer during Saturday night's game against the Chargers.

Carson Palmer wanted it back, that deep ball he heaved down the sideline to wideout J.J. Nelson in the first quarter Saturday.

His rookie speedster had gained a step on cornerback Richard Crawford, but the veteran quarterback has thrown countless bombs in his career, and knows an overthrow when he lets one fly.

Except, this time, he was wrong. As the ball ended its descent, Nelson sat there waiting for it, actually slowing down in order to complete the 57-yard gain.

"I can't wait to watch it on film," Palmer said. "He must have hit the nitrous button because he took off."

When the Cardinals selected Nelson in the fifth-round of the draft, they knew he had speed. The Alabama-Birmingham star had the fastest 40-yard dash at the NFL Scouting combine and figured to come in and compete for kick and punt return duties immediately.

His playing time at wideout was less certain, with Michael Floyd, Larry Fitzgerald and John Brown taking up the majority of the snaps and Jaron Brown and Brittan Golden battling Nelson for the fourth receiver spot. But with Floyd recovering from three dislocated fingers in his hand, it was Nelson who started alongside John Brown and Fitzgerald in a three-receiver set in the 22-19 preseason loss to the Chargers.

"I didn't see it coming," Nelson said of getting the start.

Nelson adjusted to the NFL slowly during the summer, so awash in the technical aspects that his brain slowed down his feet. After organized team activities, he knew he had to make the most of the seven-week hiatus before training camp.

"The stuff they told me to go home and work on during the break, I went and did those things," Nelson said. "It was up to me to come out here back at camp and show them that I went home and I took coaching and I improved my game."

This is a similar story to the 2014 journey of John Brown, the small-school speedster who was drafted in the third round and made an

immediate impact as a rookie. With Brown nicknamed "Smoke," Nelson has earned the moniker "Fire," and coach Bruce Arians believes Nelson is further along than Brown was at this point.

"Smoke has taught him a lot and took him under his wing," Arians said.

When Palmer barked out the go-route play-call in the huddle, Nelson wasn't sure the ball was going to him. Brown was on the other side preparing to do the same thing, and while he's a tick slower than Nelson, Brown has shown plenty of ability to get behind defenses.

That dilemma for opposing defenses is why this year's offense could have the highest ceiling since Bruce Arians took over in 2013.

"I don't know how we could add any more speed to the offense," Arians said.

Nelson's speed is striking because he doesn't just get behind defensive backs but leaves them in the dust. Tyrann Mathieu and Patrick Peterson are elite defenders, and Nelson has flown past them at times during training camp.

"If you beat Pat a couple times you should get a little confidence because it doesn't get much tougher than that," Arians said. "Pat doesn't slack off. He takes that very seriously. So that's great competition for him."

Arians loves the deep ball, and tried to get Nelson one in the preseason opener against the Chiefs. Quarterback Drew Stanton chose a checkdown that day, so Nelson had to wait an extra week until Palmer's shot.

"I was so nervous, but nervous is a good thing," Nelson said.

Opposing defensive backs may feel differently after watching the tape.

"It was a confidence-booster, and there's hopefully more to come," Nelson said.