In a continuation of the Redskin youth movement along the offensive line, third year pro Jeff Williams will be given a chance during the team's current training camp to earn a starting spot at guard.

Williams, a 6-foot-4, 270-pound athlete blessed with fine quickness for such a big man, was moved from tackle to guard Sunday, the first day he reported to camp. The switch is an effort to get the five best linemen starting on the same unit.

If Williams develops over the next six weeks, he most likely would replace Ron Saul, a 10-year veteran who has been starting at left guard since coming from the Rams in 1976.

The other starting guard, Dan Nugent, is sidelined with a lower back injury that so far has defied specific diagnosis. He irritated his back this morning and did not practice the rest of the day.

"I hurt it lifting weights a couple of months ago," said Nugent. "It just hasn't gotten better. It's a mystery. No one seems to know what is wrong with it.

"I guess I'll have to see Dr. (Stan) Lavine and see what he thinks. Treatments don't seem to be helping it. It's getting pretty discouraging."

With Nugent sidelined, Williams was running with the first unit today. He says he never has played guard and when he was told he was switching from tackle, "It was probably the biggest shock of my life. I couldn't beleive it."

So he is going through a born-again football change. With Ray Callahan, the line coach, "practically my own private coach on every play," Williams is trying to carefully pick up the nuances of the new position.

"I quess it's obvious they must think I have a chance to do something at guard or they wouldn't have moved me," he said. "It's a challenge, no dubt about it. It will mean a lot of extra work because everything is so different.

"I had never envisioned myself as a guard.I've always been a tackle and I came here this year figuring I'd have a shot at tackle. Now I have to adjust to this.

"They think my attitude may not be right because of the change, but that's not true. I'm willing to give it a go."

Williams' attitude has been one of his stumbling blocks. Afteer being traded to the Redskins from the Rams last year in the Eddie Brown deal, he at first failed to report. When he finally did, he stayed for a week, then left and did not rejoin the club until early in the regular season.

When George Starke went down with a knee injury and Fred Dean was knocked dizzy on the opening kickoff of the Colt game, Williams suddenly found himself a starting tackle for the rest of the season. It was, he admits now, an awakening experience.

"Until this move to guard, that has to be the biggest surprise," he said. "It was a heck of a way to break in.

"I did some things well, but I would say I didn't play up to NFL standards most of the time. But it would have been hard to do.

"Do I regret not reporting to camp? Well, as I look back at it, I probably do. Sometimes you wish you can do things differently. I made a mistake but that is in the past.

"I came here wanting to play football."

The Redskins would like to improve both their size and quickness along the line. Williams, though not as strong as Saul, did improve himself through weight-lifting in the offseason.

Last year, new Coach Jack Pardee worked Nugent and center Bob Kuziel into the starting lineup. With that line playing well, the club got off to a 6-0 start before Starke was hurt. One of the club's goals coming into this camp was to solidify the line, if possible, with younger players.

While shuffling Williams, the Redskins also are trying free-agent guard Greg Dubinetz of Yale at tackle and moving Jim Harlan to guard from tackle and Dean from tackle guard.

"We've got to come out of this camp with the best possible linemen," said Callahan. "We want to see if these changes can pay off.

"Jeff Williams has really good talent. He is big, he can run, he is quick. I'm happy with his attitude right now, too. Missing training camp last year hurt him but he's stronger now. He's got fine potential."

Pardee was pleased with how weightlifting improved Williams' upper body strength. "We just have to find out if he can play and how good he is," said the coach.

After 10 years in the league, Saul is used to being challenged for a job. He said this time was "no different."

"Jeff is yoyng and he has talent," he said. "Could be they just want to find out if he can swing from guard to tackle.

"I don't feel anyone breathing down my neck right now. I expect to be pushed every year, especially when you start getting up there in years. But I still feel I can play. I feel good coming in here."

Williams already proved his mettle by managing to make it across country in a van, despite the gas crisis. Twice, he almost found himself marooned.

"Once, I was in South Dakota at 5 a.m. and I was on E," he said. "I went over a hill and there was a station on the other side.

"The other time was in Connecticut. I was the wrong license plate for that day. I told the guy that I didn't know anything about odd-even, I was from California. He agreed that I wouldn't be crossing state lines just to buy gas. He gave me some."

Free agent tight end Bill Helms, who has been hobbled by a hamstring pull, left camp. He was one of three tight ends from San Diego State trying to make the team. . . Mike Curtis missed both workouts because of stomach pains . . . Coy Bacon, the normally talkative defensive end, say he is not talking this year. "I don't want to be a malcontent anymore," he said. "I'll let my playing do my talking for me." Bacon is trying to beat out Karl Lorch for a starting job. $ the Redskin players say that there is a lot more hitting a lot earlier this year than in past training camps. "We aren't wasting any time," said linebacker Pete Wysocki. "There is a lot of good contact work. But that will get us sharp" . . . Best hit of the day was supplied by cornerback Ricky Harris, who straightened up and dumped a ball carrier with one mighty shoulder block. CAPTION: Picture, Jeff Williams