The Redskins know St. Louis is preparing pro football's version of the one-two punch for them today. Soften them up by running at the gut of the defense and then knock them out with quick, long-pass blows.

And why not? Every other Washington opponent this season, save for the lowly New York Giants, has employed similar strategy with great success against the Redskin defense. Even the Giants threw touchdowns of 32 and 35 yards against the No. 1-rated secondary in the league.

The Cardinals (2-4) certainly have the weapons to apply this two-fold approach. Ottis Anderson is a better runner than Jim Jodat or Otis Armstrong or Kenny King, all of whom already have gained at least 100 yards against the Redskins. And Jim Hart, when he gets into one of his hot streaks, can throw consistently long to the likes of Mel Gray and Pat Tilley.

Still, the Cardinals may have a problem with those tactics for this 1 p.m. game at RFK Stadium (WDVM-TV-9). Their offensive line is battered and bruised enough that it may not be able to provide either the blocking Anderson needs or the protection the aging, not-very-agile Hart requires. The odds-makers even make the Redskins 3 1/2-point favorites.

"Their line is a lot like ours was against Oakland," said Coach Jack Pardee, whose 1-5 team will be out to break a four-game losing streak. "They've got some key people injured and things aren't really very settled. You'd like to think we can take advantage of that, but you never know. I do think it's important for us to get off to a fast start before the line gets some confidence in itself. And it's really important for us to score some points. They've moved the ball on everyone they've played and we are going to have to keep up on the scoreboard. We can't come up emptyhanded all the time."

Today's affair marks the start of a four-game stretch of games against opponents with records of .500 or less. The players realize if they can't beat clubs like St. Louis, this season will turn out even worse than it is now.

This is also the Redskins' first home appearance in three weeks. They are 0-2 in RFK this year and, considering their poor showing so far, they aren't sure how well they will be treated by their fans.

"I think they will be good to us," Pardee said, "but we have to do something to get them yelling and to get them behind us. We have to win their support."

At one time, St. Louis could boast one of the best offensive lines in the league. But no more. Guard Bob Young was released before the season and, since then, tackle Keith Wortman, guard Tom Stieve and center Tom Banks have been lost to injuries. Guard Joe Bostic, brother of the Redskins' kick snapper, Jeff, is hobbled and will be playing at less than full strength if he gets into the game.

St. Louis will have a new kicker, former Buc Neil O'donoghue. He replaces Steve Little, who was cut during the week, then seriously injured in a car accident early Friday morning.

The injuries and changes have put additional pressure on Anderson, the conference's No. 3 rusher who is averaging five yards a carry. It's much easier to run-block than pass-block with a makeshift line, so the Cards should be concentrating on controlling the game with Anderson's running. That would prevent the Redskins' inconsistent pass rushers from teeing off on Hart.

That's why middle linebacker Neal Olkewicz looms as an important figure for Washington. His job will be to shadow Anderson.

The Redskin offense, although closer to full strength and more diversified than at any point this season, still has injury problems. Clarence Harmon has laid off his sore ankle this week, and says he will play. But similar ankle injuries have kept Harmon and other Redskin runners on the bench this year, and it wouldn't be surprising if most of the fullback work load falls to Rickey Claitt, back from his own ankle ailment, and Buddy Hardeman.

The Washington defense also can't seem to shed its problems. This season is particularly frustrating for Pardee, a defensive specialist, and for his defensive coaching staff. Opponents are exploiting areas the Resdkins had hoped would be more solid than last year, when teams broke off too many long passes in the 30-yard range and had too much success on the ground for the unit to gain any stability.

Hopes for improvement have been hindered, in part, by a lackluster showing so far from the front four, by injuries to the linebackers and by the unit's obvious lack of quickness. In some spots, they have inferior personnel, especially against the run. And defensive end Coy Bacon's knee is sore, which could reduce his quickness.

Even with these troubles, Washington might be able to perform better defensively if its talented, much-praised secondary could cut off the long passes. Statistics illustrate just how susceptible the Redskins have been to the bomb. The Redskins have allowed opponents to complete 68 passes this year for 887 yards. Sixteen of those completions have been for 19 or more yards, or 438 hards total. So only one-quarter of the completions have accounted for almost half of the yardage surrendered.

"The problem is that you get so run-conscious that the long pass can hurt you," linebacker Brad Dusek said. "But I still think most of the problem stems from our inability to play a complete game. We go really well for a while, then things will break down. We can't seem to be steady for a full 60 minutes."

Changes in the starting lineup eventually will improve the run defense, but the Redskins already have the talent to clamp down on the long passes. Pardee says at the moment, however, his defense is coming up short in a shifting game of odds against opposition quarterbacks.

The irony of this game is that the Redskins had a built-in incentive to win, even before the season began, only to see it wiped out by their horrid start. If Washington was playing as well as had been expected, there would have been considerable talk about how the Cards performed in that season-ending 42-6 loss to Chicago that helped cost the Redskins a playoff spot.

But the players admit that it's tough to spout off about revenge when they are struggling just to win one game, any game.

"If we don't take care of our own business and play well," said Dusek, "then revenge isn't going to matter at all."