By necessity, not design, the Washington Redskins play another in their continuing series of "must games" tonight as a changed team.

Because injuries have chosen to hit the hardest at the worst time, the Redskins (5-5) will start another rookie -- strong safety Raphel Cherry -- against the division-leading New York Giants (7-3) at 9 p.m. at RFK Stadium.

Cherry, who has been playing backup free safety all season, will replace veteran Tony Peters, who has a pulled groin, Coach Joe Gibbs said yesterday.

It's also likely, although not a sure thing as of yesterday, that middle linebacker Neal Olkewicz (torn right pectoral muscle) will not be able to start. That decision will be made in pregame drills.

In that case, Rich Milot would move to the middle and Monte Coleman, who says he is running at about 75 percent of full strength because of a strained right hamstring, would replace Milot on the right side.

That's not all. Defensive end Dexter Manley, who was in bed for two days with the flu earlier in the week, trudged off the practice field yesterday and smiled wanly when asked how he felt.

"Still kind of weak," he said.

"We think he'll be ready to go," Gibbs said.

Running backs John Riggins (stiff back) and George Rogers (sore left shoulder) both have been practicing, but neither is totally healthy. Riggins is expected to start.

And the left side of the offensive line has been remodeled, with guard Russ Grimm moving to tackle and center Jeff Bostic to guard. All-pro tackle Joe Jacoby will miss his fifth game with a sprained right knee.

What a way to meet the hottest team in the NFC East.

"The toughest thing is adjusting (in practice) to guys who you're not sure will play, to guys who are kind of touchy because of injuries," Gibbs said.

It's been said before during this season (against Chicago, St. Louis, Cleveland and Dallas) that the Redskins were playing a game they must win. They're 2-2 so far in these.

Because they were tied with four other teams for the final wild-card spot in the NFC going into yesterday's games, even this game is no more than a must win with an asterisk. There still are too many games left and too many mediocre teams to give one the ax if it loses in Week 11.

But, if it's quality of life we're talking about, not just staying alive, then the Redskins need a victory in the worst way.

They have not beaten a team over .500 (heading into this weekend's games) this season. Their passing offense still is last in the National Football League. They lost to the Giants miserably, 17-3, four weeks ago. They have won only one of five division games.

Since they met the Redskins, the Giants have not lost. They are going for five in a row tonight, and the last time they did that was in 1970. Their defense, led by end Leonard Marshall and linebacker Lawrence Taylor, is ranked No. 1 in the NFL.

The Redskins, the league's top rushing team, gained just 69 yards on the ground in their October game with the Giants, their lowest total of the season. They tried to run only 19 times, also a season low.

When they threw (which was often because they got behind), quarterback Joe Theismann was intercepted three times, twice in the Giants' end zone, and was sacked seven times.

The Giants say they are looking forward to this rematch. Gibbs knows it.

"You've got a very good defense and a struggling offense," he said. "The first game, they handled us. Look at it. The stats tell you."

It's not all Giants defense versus Redskins offense, either. New York quarterback Phil Simms, having a fine season, has completed just 20 more passes than Theismann but has thrown for 800 more yards.

But there are reasons for Redskins fans to watch this game. The Giants have a history of falling apart at about this point in the season.

The last time they played, the Redskins were missing not only Jacoby but receiver Art Monk as well. Monk is back and healthy now.

Plus, there's the emotion of a Monday night game at RFK, in which the Redskins are 9-2. Put into this same situation more than a month ago against the Cardinals, the Redskins romped, 27-10.

"You either stand up or you run," Gibbs said this week.

But will the Redskins be able to push themselves over .500 with all these new people? A team can accommodate an occasional change -- a Dean Hamel for a Darryl Grant, a Gary Clark for a Calvin Muhammad -- but can it continue to function with injury and adaptation in nearly every area of the field?

For Cherry, a quarterback at the University of Hawaii at this time last year, the starting assignment is not altogether a surprise. But the position is. He moved to strong safety only this week, when Peters missed practice.

"I guess I'll have to mess around with linemen now," Cherry said yesterday. "I've just got to go in and hit somebody. At free safety, you sit back, wait and watch. This will be different."

The Redskins know the Giants will see if Cherry is up to this task.

"It'll be no problem," said assistant head coach/defense Richie Petitbon. "We knew he'd be in there (one day), but we didn't think he would be playing strong safety. It's just one of those things."

Guard R.C. Thielemann, who has a torn ligament in his right knee, experienced pain when he practiced this week, assistant head coach/offense Joe Bugel said. "The prognosis wasn't good in his mind," Bugel said.

Thielemann is expected to undergo knee surgery in Atlanta if he can't play. Bugel said he expects him to practice again this week before he makes a decision on surgery.