For the fifth time this season, the Washington Redskins have changed quarterbacks. Veteran Doug Williams will replace Jay Schroeder as the starter for the upcoming National Football Conference semifinal game, Coach Joe Gibbs announced yesterday.

But Gibbs put off until next week his decision on who will kick extra points and field goals in the Jan. 9 or 10 contest. He said he wants to watch Ali Haji-Sheikh and Jess Atkinson kick "side-by-side" in practice before picking one of them to kick in the playoff game at San Francisco or Chicago.

Haji-Sheikh's job is in jeopardy after he missed two of four field goal attempts in the team's victory at Minnesota Saturday. Atkinson, who joined the Redskins for the regular season finale last year and was the team's kicker through the playoffs, has recovered from a dislocated left ankle he suffered in the season opener Sept. 13 and apparently is ready if Gibbs calls on him.

As the players and coaches returned to Redskin Park after a three-day break to begin practicing for the playoffs, Gibbs discussed his plans at other positions. He stuck by his decision to keep four-time Pro Bowl offensive lineman Russ Grimm on the bench in favor of continuity along the offensive line and said he plans to continue a rotation system among running backs George Rogers, Kelvin Bryant and Timmy Smith.

But the hot topic of the day at Redskin Park was the quarterback situation. As Williams and Schroeder walked out to practice yesterday afternoon, they knew nothing more than they knew after the Redskins' 27-24 overtime victory over the Vikings, when Williams led the team to 20 points in 24 minutes after replacing Schroeder.

But when Gibbs said, "Doug, take five snaps. Jay, take five snaps," in that order, Williams said he knew he had the job.

"After practice, as we walked off the field, he told me he was going with me in the playoffs," Williams told reporters. "But I knew as soon as practice started."

Williams, a starter for five seasons with Tampa Bay from 1978-82, said the opportunity to start in the playoffs "means a lot" to him.

"I want to play and quite obviously, this is my opportunity," he said. "This has been a crazy season but also a good season for Doug Williams. It has given me the opportunity to play and show people that Doug Williams can play. I think after last season a lot of people did not know what had happened to me after Tampa Bay."

This will be Williams' third starting assignment of an emotional, unpredictable season. Called upon to relieve Schroeder in games against Philadelphia, Detroit and Minnesota, he led the Redskins to three victories. In games he has started, the Redskins are 0-2, having lost to Atlanta, 21-20, and to the Los Angeles Rams, 30-26. But the kicking game squandered four potential points in the Falcons loss and wide receiver Art Monk dropped two passes in the end zone in the final minute of the Rams loss.

Williams first got the starting assignment when Schroeder sprained his right shoulder early in the season opener. After the strike, Schroeder was healthy again and Williams went back to the reserve role.

But Schroeder did not play well, overthrowing numerous open receivers in games against Philadelphia and Detroit before being benched by Gibbs with seven minutes left in the first half against the Lions. Williams started the Redskins' next game, against the Rams, but injured his lower back during practice on Thanksgiving Day and was replaced by Schroeder.

Schroeder led the Redskins to a fourth-quarter comeback against the New York Giants that week, regaining the starting job for the following three games.

On Nov. 30, when Williams spoke with reporters after being told he no longer was the starter, his voice choked with emotion and tears welled in his eyes.

Now, he is back on top of his world, while questions again are surrounding Schroeder, a Pro Bowl player last season, who has run into tough times this season. Yesterday, Schroeder left before the news conference announcing the decision and could not be reached for comment afterward.

Gibbs offered Schroeder's lack of "accuracy" as the problem. But Schroeder has never been known as a particularly accurate quarterback. Schroeder completed 48.3 percent of his passes this season. In 1985, his completion percentage was 53.6; in 1986, 51 percent.

Williams was calm yesterday, although he is allowing himself to wonder what might happen if the Redskins make it to the Super Bowl.

"I think a Super Bowl would mean probably more for me, not so much from a personal standpoint as it would for black America," Williams said. "The media would make a bigger deal out of it than I probably would simply because it'd be the first black quarterback to get an opportunity to play in the Super Bowl.

"But I think for myself, it'd be just like anybody else getting an opportunity to play in the Super Bowl. That's the ultimate dream of anybody who's in the National Football League."

In other developments, head trainer Bubba Tyer said Monk jogged yesterday for the first time since injuring his right knee Dec. 6. Monk said it would be "hard" for him to be ready for the first playoff game, but Tyer said he has not yet been ruled out for the game.

Tyer also said center Jeff Bostic has a sprained lower leg. Bostic received a vote of confidence from Gibbs when the coach said Grimm would not regain his starting job from Bostic for the playoffs.

Grimm said yesterday he "didn't like" the decision, but would abide by it.