CHARLOTTE – When offensive linemen are playing well, they often go unnoticed.

But a couple of bad snaps can define a four-quarter performance, and that's especially true for left tackle Matt Kalil, who will be in the spotlight this week with the Vikings -- his former team -- coming to Carolina.

"That's the nature of his position," offensive coordinator Mike Shula said of the highest-priced free agent acquisition in franchise history.

Sunday's game against the Saints was always going to be a challenging one for Kalil, who was matched up against Pro Bowl defensive end Cameron Jordan in a hostile environment.

The fact that Kalil was battling an illness didn't make things easier.

"He came in just before the game and got some medicine and an IV before he played," head coach Ron Rivera said. "He gutted it out and played every snap."

And while there were good moments both in the run game and pass game, two plays and three penalties became the focus of Kalil's performance.

In the second quarter, he held Jordan, wiping away Cam Newton's scramble to move the chains on third down. In the fourth quarter, Kalil was penalized for holding Jordan and grabbing his facemask on the same play.

"There are a couple plays he may have wanted back," Shula said. "But there are some other times with him as our left tackle, and our whole line, that allowed Cam to go through his progressions."

Shula pointed out two plays in particular where Newton was given ample time to survey the field.

Wide receiver Kaelin Clay was the third read for Newton on third-and-3 on Carolina's first drive of the game. They connected for a 13-yard gain.

Running back Christian McCaffrey was the fourth read on third-and-4 late in the second quarter. Newton found him for a 21-yard touchdown.

Those completions speak more to the success of the line as a unit, but the left tackle is always singled out. It's why the Panthers invested so much in an attempt to stabilize the position.

Kalil hasn't been flawless by any stretch, but Shula and Rivera have shown confidence by trusting him in one-one-one situations. The Panthers haven't slid the protection or relied on chips as much as they have in the past.

"I'm thrilled that we have him. We're lucky to have him," Shula said. "We're not sitting there every week saying, 'We have to – by scheme – continue to constantly give our left tackle help.' I'm not saying we had to do that all the time last year. But we feel like we've got a good matchup for most weeks going in there with him."

Added Rivera: "Pass protecting, I think he's done some really good things. Some of the things he struggles with are the pure athletic speed guys that convert it to power. That's one of the things he continues to work on and gets better and better at."

It's a new system for Kalil, which takes some time to get used to, and he's striving for consistency in his technique.

His contract and his position come with increased scrutiny, and there is only one way to please everybody, especially with a matchup against Minnesota up next.

"He's got to continue to get better," Shula said.