Lane Johnson was the No. 4 overall pick in the 2013 draft, he played left tackle while at Oklahoma, but has been used strictly as a right tackle since joining the league.

Until now.

The Eagles downgraded starting left tackle Jason Peters to out for the game against the Cowboys, so Johnson will make his debut in the NFL as a left tackle this week against Greg Hardy.

"Well, usually he takes zero," Eagles head coach Chip Kelly said Thursday when asked if Johnson had taken more reps at left tackle this week at practice.  "So, yes, he's taken more snaps than zero."

Peters was carted off with "back spasms" on a non-contact play on the Eagles' third drive of the game against the Panthers.  It initially had the look of a more serious injury, but Peters said he will be "all right" after the game, leaving the window open that he would play this week.

When Peters was asked if he would be able to play this week after the Carolina game, Peters responded, "Yeah."

Unfortunately, that's not the case, so the Eagles will turn to Johnson instead of Matt Tobin who moved to left tackle two weeks ago in Carolina.  Tobin is the starting right guard, so instead of moving him out to tackle and Dennis Kelly into his guard spot, the Eagles will kick Kelly out to his more natural right tackle position.

While John has played left tackle in college, he has been used only at right tackle in the NFL, Kelly said there are differences in playing the right side and the left side.

"Stance, pass rushers that you're going to face and the ability to operate your feet in a different manner," Kelly explained. "But really matchups, I think, is really what it comes down to."

This matchup with be a tough one for Johnson, who will be face-to-face with Hardy, one of the top pass rushers in the league, but the Cowboys could move him to the other side of the field to get him matched up with Dennis Kelly who doesn't have a lot of NFL experience playing tackle.

"They are moving him around," Kelly said.  "You'll get him inside and get him in some matchups, but predominantly he's been at the strong-side outside, defensive end for them. But they have moved him around a little bit."

Dennis Kelly has started 13 games in the NFL during his four seasons, but most of that action has come at right guard, but he was a tackle in college, so that's where he seems to be more comfortable.

"I think he’s done a nice job because he's gone in at guard for us," Kelly said. "That's where we've seen him, and [we] haven't seen him unless it was preseason games at tackle."

 (Listen to John McMullen talk about the Eagles vs Cowboys matchups)