The Cardinals are dealing with their first significant injury of training camp.

Inside linebacker Haason Reddick had arthroscopic surgery on his knee and will miss "a few weeks," coach Kliff Kingsbury said. Defensive coordinator Vance Joseph said Reddick will be back in time for the team's regular season opener on Sept. 8 against the Lions.

Reddick, the team's first-round pick in 2017, is projected to be a key piece in the middle of the defense this season.

"We feel fortunate that we will have him back, but it will be a few weeks," Kingsbury said.

Backup Dennis Gardeck, who made the team as an undrafted free agent a year ago for his special teams prowess, is working with the first team in Reddick's absence. Kingsbury said Gardeck turned some heads in the offseason.

"He's a guy who shows up early, extra hard worker, very football intelligent," Kingsbury said. "We're all anxious to see how he handles this."

The Cardinals used several different combinations at linebacker in 2018, but Gardeck was not able to break into the rotation. If he fares well over the next few weeks, Gardeck figures to be the top reserve option at inside linebacker.

"That's what you play for," Gardeck said. "I appreciate them trusting me and giving me that opportunity. Now it's my job to come through and show that I'm able to step in if there is an injury."

Gardeck will be working alongside middle linebacker Jordan Hicks during Reddick's absence. Hicks is no stranger to injuries after missing 13 games the past two seasons.

"It sucks that (Reddick) is hurt, but we've all been there," Hicks said. "We're there for Haason, but at the same time, it's an opportunity for someone else to get those reps and see what they can do against the (starting) offense. It's exciting for Dennis. He's done a good job."

Gardeck is trying not to put too much pressure on himself with the increased responsibility.

"One thing I learned from my rookie year is, don't ride that roller coaster," Gardeck said. "Never too high. Never too low. Just approach each day with clear eyes and make the most out of every opportunity."

SWEARINGER HAS SOFT TISSUE INJURY

Safety D.J. Swearinger missed practice on Friday with a "soft tissue" injury, but Kingsbury doesn't expect it to be a serious issue. Josh Shaw and undrafted free agent Tyler Sigler saw work with the first team in his absence.

Defensive tackle Vincent Valentine was injured Friday but is not expected to be out long, Kingsbury said. Kingsbury didn't specify the injury but Valentine had grabbed his knee when he went down after a play in practice.

Outside linebacker Brooks Reed was activated from the physically unable to perform list prior to Saturday's practice after missing the first three days with a hip issue.

PADDED PRACTICES BEGIN

After months of practicing in shorts and t-shirts, Saturday marked the first padded practice of 2019 for the Cardinals. Kingsbury said the team wouldn't be tackling to the ground, but he was ready for the practices to be "more like real football."

"I'm just excited to see the physicality of the practice, and how we respond on Day One," he said.

Guard J.R. Sweezy, known for his competitive fire and willingness to play through the whistle, is a player that Kingsbury said he may have to hold back.

"I love this part of it," Sweezy said. "I've been looking forward to this for a long time."