The Redskins' coaching staff began preparations yesterday for Washington's opening playoff game against Detroit with major injury questions at running back and receiver that likely won't be answered fully until just before Saturday's 12:30 p.m. kickoff.

"We are scratching and scrambling, trying to get ready," said Coach Joe Gibbs, who admitted the Redskins' injury situation was by far the worst of the season.

Receiver Art Monk (broken bone in foot) is out for the playoffs. His replacement, Virgil Seay, still is bothered by a pulled muscle in his hip and, according to Gibbs, probably won't play Saturday. Running backs John Riggins (pulled thigh muscle), Joe Washington (sore knee) and Clarence Harmon (strained knee) all are limping, although Gibbs said he expects Washington and Riggins to recover by the end of the week.

If Seay can't play, Gibbs said, Alvin Garrett probably would start, with Charlie Brown moving to Monk's flanker spot.

But with so many injuries at two positions, Gibbs was unable yesterday to decide what roster moves he wanted to make. He likely will put Monk on injured reserve to create a roster spot, which could be filled by either a running back (Wilbur Jackson) or a receiver. Gibbs is hesitant to sign a free agent receiver, since the player would have only a few days to learn the Redskins' complex passing system.

"We are going to go over Detroit, then our game plan and then see how our personnel fits in before we decide exactly what we will do," Gibbs said. "We are just going to have to do the best we can and be ready."

The injury situation added to the Redskins' unhappiness over having to play Saturday instead of Sunday, as Gibbs would have preferred. Gibbs and General Manager Bobby Beathard both called the league office last week, requesting that the NFC's No. 1- and 2-seeded teams be given Sunday playoff dates. Yesterday, the NFL gave the Redskins the Saturday date.

"The decision has been made, but we don't think it has been made for the right reasons," said Gibbs, whose team is seeded No. 1. "It should be clear-cut that the No. l and No. 2 seeds should be playing Sunday.

"They (the league) said it was because of the weather. They felt like if there was a 4 p.m. game on Sunday, the odds were better that the weather in Atlanta would be better than in Washington. I'm looking at the Cotton Bowl and it's 60 degrees here and snowing in Dallas. It's all like blowing in the wind.

"It would have helped us to have an extra day because of injuries . . . We had gotten into a weekly groove with our routine and it hadn't changed all season. We played every week on Sunday. Now all that has changed."

What hasn't changed is the seriousness of the injury problem, which has particularly affected Washington's offensive unit.

Gibbs said he was considering several options at receiver to provide depth behind Garrett and Brown. Tight ends Clint Didier, a former wide receiver in college, and Rich Caster, a former wide receiver with the New York Jets, both probably will practice at the receiver spot this week. They also give the Redskins needed size at the spot, since neither Brown nor Garrett is taller than 5 feet 10.

Halfback Nick Giaquinto and tight end Rick Walker shared Monk's third-down, man-in-motion responsibilities Sunday against St. Louis and could do the same this week. The Redskins won't move Joe Washington to receiver, Gibbs said, but he would like Washington available as a third-down receiver coming out of the backfield.

"I'm not sure if this will cut into what we can do with our offense," Gibbs said. "You hate to do that by losing just one person. But Art meant so much to our team and our offense. It's something we have to examine."

Riggins did not play against St. Louis after his thigh tightened during pregame warmups. He hardly played against New Orleans the week before after the injury acted up in the first quarter.

"I thought that the leg would loosen up and get better with treatment," Gibbs said. "I guess I'm more pessimistic about it now . . . But I probably think both Joe and John will be available."

Washington is bothered by swelling in his right knee, but played some against St. Louis. He had an operation on his left knee at the end of training camp. Harmon's knee is strained and will be examined by team doctors today.

"We went through this type of strained situation over injuries every week early last year but we had gotten away from it this year," Gibbs said. "It really affects your routine and your concentration . . . This is when you want everything going smoothly and it isn't. We just have to cope with it."

Even with the best NFC record, the Redskins feel they still have to establish credibility in the playoffs, another reason the injuries have hit the coaching staff so hard.

"All I know," said Gibbs, "is that for us to win the Super Bowl, we'd be 12-1 on the year. I don't think that can be considered a fluke. It would be a legitimate achievement."

Cornerback Vernon Dean (fractured wrist) is the only defensive player with a new injury. He will play Saturday wearing a leather brace. His wrist currently is in a Fiberglas cast . . . The Redskins set a team record by throwing only nine interceptions this season, breaking the previous mark of eight, shared by the 1945 and 1970 teams . . . Washington's 64-percent completion percentage tied the 1945 record . . . St. Louis gained only 41 rushing yards Sunday, the lowest against the Redskins in a decade. Washington gave up 105 rushing yards a game, best since 1974 . . . The Redskins have won 11 of 12 games and 16 of 20. They finished with a four-game winning streak, the first time that's happened since 1942 . . . This will be Washington's sixth trip to playoffs in the last 12 years, but first since 1976. Grand Prize: $70,000 Each

Each of the Washington Redskins would make $70,000 from the playoffs if the team wins Super Bowl XVII, under terms of the new collective bargaining agreement between the National Football League and the NFL Players Association.

For playing in the first round Saturday against Detroit, each will receive $6,000, win or lose.

If the Redskins reach the second-round game Jan. 15 or 16, each player will receive $10,000, win or lose.

If Washington plays in the NFC title game Jan. 22, each player will receive $18,000, win or lose.

In the Super Bowl Jan. 30 in Pasadena, Calif., winning players will receive $36,000 and losing players $18,000.

Under the last collective bargaining agreement, players could make $3,000 for the first round, $5,000 for the second, $9,000 for the championship game, $18,000 for winning the Super Bowl and $9,000 if they lost. The most a player could earn was $35,000.