Either Saints coach Sean Payton doesn't want to tip Baltimore off as to who'll start in New Orleans' secondary on Monday night, or he really doesn't know yet.

Both scenarios are possible in the wake of Rafael Bush's season-ending leg injury and top cornerback Keenan Lewis' ongoing recovery from a knee bruise.

"We will look at the workweek and make sure we are putting the best combination together," Payton said Thursday. "Part of a long NFL season is attrition, sometimes to injury, and the next guys up will have to do the job."

The Saints have several candidates to take over for Bush, among them Marcus Ball, a former Canadian Football League player who had a hamstring injury earlier this season and has seen most of his action on special teams since returning to health in early October.

"He is smart. He is healthy," Payton said. "He certainly knows and has a good grasp of what we are doing."

The Saints' other safeties include Jamarca Sanford, a former Minnesota Vikings starter who was signed last week, and Pierre Warren, who was signed this week off of Minnesota's practice squad, but who was also with the Saints during training camp.

Saints strong safety Kenny Vaccaro said he remembers Warren "making a lot of plays" in camp, adding that he is "a guy that's already around the ball so that's always good."

Bush began the season as New Orleans' primary backup safety, but moved into a starting role after a season-ending knee injury to top offseason acquisition Jairus Byrd.

Now New Orleans is on its third free safety at a time when the defense has been struggling, ranked 24th against pass, allowing 255.2 yards per game.

Complicating matters is Lewis' status. He hasn't let his knee injury keep him out of a game entirely, but he has missed a lot of snaps in the past two games and sat out practice on Thursday.

"I'm making progress, but it's nowhere near where I want to be," Lewis said. "That's my main goal right now, just to get to where I want to be."

To add depth at that spot, New Orleans this week brought up Terrence Frederick from the practice squad.

Cornerback Corey White was a safety in college and even practiced a bit at that spot during training camp last August.

If the Saints really needed him to move from cornerback to safety, White, who has two interceptions, is confident he could do it.

He just doesn't think New Orleans' necessarily needs to take such a step yet. The healthy safeties still on the roster can do the job, White insisted, even if they haven't had much experience in defensive coordinator Rob Ryan's system this season.

"They're smart and if they weren't smart and couldn't play they wouldn't be here, trust me," White said. "We'll be fine."

White added that Ryan, who is known for fielding some exotic, complicated defenses, has been flexible in drawing up his weekly schemes to account for players' strengths and weaknesses.

So when a new player enters the lineup, "He doesn't make the plan difficult for that person," White said. "I wouldn't expect any complexity at all, especially being that we've got some guys banged up."

Vaccaro, meanwhile, downplayed the potential problems that can arise from a new player lining up alongside him in the defensive backfield.

"We can plug guys in and they can play," Vaccaro asserted. "We have the depth to do that."

As for how quickly any of the new safeties truly learn to excel in Ryan's scheme, Vaccaro said, "It depends on the player. I was comfortable from Day 1 as a player. It depends on the time you put in and how great you want to be."

Notes: RB Pierre Thomas, who has missed the past four games with shoulder and rib injuries, returned to practice on a limited basis but stopped short of saying whether he might play Monday night. "I did not think it was going to take this long, but hey, I had to make sure it was right, and I still have to make sure it's right before I step out on that field, so I don't have any setbacks," Thomas said. "I don't want to put myself out here and play one game and get hit and then that's it. No, I want to finish this season out and then continue on into the playoffs, too." ... WR Robert Meachem also was limited. ... RT Zach Strief, who left last Sunday's game with concussion symptoms, practiced fully, as did RB Mark Ingram, who'd been limited in practice in recent weeks because of shoulder soreness. ... Those sitting out practice included LB Curtis Lofton (ankle), RB Khiry Robinson (forearm), Travaris Cadet (hamstring) and LB Kyle Knox (hand).

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