The Redskins aren't certain whether tackle Wilbur Young or cornerback Lemar Parrish will be able to play against Dallas Sunday, adding to a defensive injury situation that coordinator Richie Petitbon yesterday called "really scary."

"We'll be okay as long as no one else gets nicked," Petitbon said. "But we are very, very thin. It's tough going into a game like this without much depth. You always expect someone to go down."

The Redskin defense, which had limited depth before the injuries, already has lost linebacker Brad Dusek with a dislocated shoulder. Safety Mike Nelms can play, but he is hampered by a broken right thumb. And defensive end Mat Mendenhall has a sore knee.

Parrish, according to Petitbon, might start. Even if he does, the Redskins aren't sure how long he will last. And if Parrish is sidelined, Washington's nickel defense also will suffer.

"He's had problems with the leg for three weeks now," Petitbon said. "I was hoping it would come around this week so he could work out. But he hasn't. Your physical condition has to suffer with that much time off, so I'm not sure what he can take. At this point, I'm not sure he can even play."

If Parrish comes out, veteran Jeris White would take his place. Safety Tony Peters also can play cornerback, but with Nelms hobbled, Petitbon's flexibility is reduced. White normally is the extra back on the nickel, a role Nelms or rookie LeCharls McDaniel would have to fill in Parrish's absence.

Parrish, however, usually recovers well enough from leg injuries to play adequately, something Petitbon hopes he does this time around, too.

Young, who says he wants to play, aggravated his sore shoulder in practice Wednesday. Petitbon said he would be "very surprised" if the ex-San Diego Charger plays against the Cowboys. Young normally would have replaced starter Perry Brooks on obvious passing situations.

With Dusek hurt, the reserve linebacking corps is rather inexperienced. Kevin Turner has seen only limited action in his one NFL year, Mel Kaufman is a rookie and Dave Graf is playing for the first time in the middle after six years on the outside.

The injuries have diminished Petitbon's ability to match up personnel to game situations. He had planned to switch frequently with his front four, especially on passing downs, using what he called a "patch-and-paste" approach. Now his ideas have changed.

"We'll have to go along with the starting front four," he said. "Dexter (Manley) will come in on some passing situations and we'll use Mat, too. We want to keep people like Coy (Bacon) and Karl (Lorch) fresh. But we can't do as many things as we had hoped."

The defensive unit had an impressive preseason, allowing only 30 points, despite the play of the front four. Petitbon and Coach Joe Gibbs had hoped Fred Cook would add to the pass rush and that Young would be a starter. Cook was cut and Young has been inconsistent against the run and hindered by the shoulder problem. He also is overweight.

Not even Petitbon is sure how much improvement the unit has made against the run (it was 27th in the league last year) or whether a more aggressive style will improve the pass rush. He feels the young starting linebackers (Neal Olkewicz, Monte Coleman and Rich Milot) have matured rapidly and the secondary is sound when healthy.

Many of the young players on offense admit they are looking toward the more experienced defense, which has only two starting changes since the start of last season, to provide leadership on Sunday.

"We know the defense can play; look what they've done in camp," said guard Melvin Jones. "Nobody is going to push them around."

But Danny White and the Cowboys are going to try. White, in his two starts as quarterback against the Redskins, has had average success, although the Cowboys won both games. Last November, in Dallas, White was intercepted five times, when the Redskins were able to control the Cowboy running game and force a number of long-yardage situations against the Washington nickel.

"Playing White is a lot like playing Roger Staubach," cornerback Joe Lavender said. "You really can't tell much difference, other than the fact Roger had so much experience. One day, White will be at that level too.

"You just always knew that with Roger, you better be prepared to play 60 minutes. He was one of the best I've ever played against. But Dallas doesn't change that much because (Coach Tom) Landry doesn't change. He's still calling the plays. You fit into his offense, not the other way around."

White made his pro starting debut a year ago against the Redskins in RFK. He played cautiously, letting the Cowboy defense do most of the work in a 17-3 triumph. But he progressed rapidly during the season, and directed Dallas to a come-from-behind victory over Atlanta in the playoffs.

"He's an established quarterback now," Petitbon said. "Roger is still Roger; there aren't many like him. But White is a good athlete, he can scramble, he's intelligent. You've got to respect the way he's come on. You always feared that Roger would make the big play everytime they needed one. Now they probably think White can do that, too."