METAIRIE, La. -- The New Orleans Saints placed cornerback P.J. Williams on injured reserve Wednesday after he was carted off the field with a concussion on Sunday.

It's unclear whether Williams suffered any injuries beyond the concussion. Saints coach Sean Payton and Williams' agent, Deryk Gilmore, both said Monday that Williams' diagnosis was encouraging after he spent the night in a New York-area hospital for evaluation.

Williams is unlikely to return this season, since the Saints can return only one player from injured reserve -- and they will likely use that designation on defensive tackle Sheldon Rankins when he is eligible after the first eight weeks.

Williams was down on the field for several tense minutes Sunday before he was immobilized against a backboard, with his helmet strapped down, and lifted onto a cart. He appeared to have been hit by two knees to the head -- the first from the leg of New York Giants tight end Larry Donnell and the second from Saints teammate Craig Robertson in the back of his helmet.

Saints cornerback P.J. Williams was carted off the field Sunday with a concussion. This marks the second time he has been placed on injured reserve since being drafted in 2015. AP Photo/Seth Wenig

Players from both teams immediately waved for trainers to come onto the field and showed support and concern for Williams while he was being evaluated.

"It's a concussion, but yet it's one significant enough that you wouldn't really see on a normal basis," Payton said Thursday. "He'll be able to make a full recovery, he'll be able to return to football in the offseason. And yet, I would say probably one of the more severe concussions that I've seen."

"He's doing better," Payton continued. "None of this will carry over and limit him in any way in the future."

This is the second time Williams has been placed on injured reserve in his young career since being drafted in the third round out of Florida State in 2015. He missed all of last season with a hamstring injury. Then he won a starting job this summer, only to go back on IR after two starts.

The Saints' cornerback position has been ravaged by injury. Their top cornerback, Delvin Breaux, suffered a broken fibula in Week 1 that is expected to keep him out for at least six weeks. Veteran Keenan Lewis was released during the preseason after a setback with his lingering hip injury. Backups Damian Swann and Kyle Wilson were placed on IR during the summer.

That leaves New Orleans with recently signed veterans Sterling Moore and B.W. Webb and undrafted rookies De'Vante Harris and Ken Crawley heading into this week's matchup against star receiver Julio Jones and the Atlanta Falcons.

That's not great considering the Saints' secondary was struggling even when it was healthier last year. The Saints set NFL records for TD passes allowed in a season (45) and opponents' passer rating (116.1).

The good news is that New Orleans' makeshift lineup played surprisingly well against the Giants and receiver Odell Beckham Jr. in Week 2. Although QB Eli Manning threw for 368 yards, the Giants didn't score an offensive touchdown in their 16-13 win over the Saints.

New Orleans replaced Williams on the roster by re-signing veteran offensive tackle Tony Hills, who has been on and off the roster since last year. Saints right tackle Zach Strief left Sunday's game early with an unspecified injury. Hills could be needed as an alternative.