Coach Joe Gibbs told the Washington Redskins at midweek that enough time had been spent fretting about that Thanksgiving Day loss to Dallas and that it was time to get on with the business at hand.

He reminded the Redskins that their season didn't end with a loss to the Cowboys and that the next five games will decide how this team is remembered. As linebacker Wilber Marshall said: "We realize it's all still there for us. If we take care of business, we're in the playoffs. We need to take whatever's in front of us and not think about what happened last week or last month."

Their immediate business is with the Miami Dolphins, who will line up at RFK Stadium at 1 today to play a game that means vastly different things to each team.

For the Dolphins (9-2), headed to the playoffs for the first time since 1985, it's a chance to keep pace with Buffalo (9-2) and stay atop the AFC East -- or to move ahead if the Bills lose to Philadelphia today. The Dolphins want this game because they'd like a bye in the first round of the playoffs, and because if they eventually play the Bills for the AFC championship, they'd rather do it in South Florida.

"We've still got a lot of winning to do before we can think about what's down the road," Dolphins Coach Don Shula said this week.

It's a challenge of another dimension for the Redskins (6-5), who have lost three of their last five games and are struggling to stay in the race for one of the NFC's three wild-card spots.

A couple of weeks ago they appeared headed for a wild-card home-field advantage, but they have since fallen behind the Eagles (7-4) and into a tie with the Packers, who have only one winning team left on their schedule. The Vikings (5-6), Saints (5-6) and Cowboys (5-7) are all still in the picture.

Defeating the Dolphins would not only help their playoff chances, it would disencumber them of a lot of baggage that comes with having beaten but one winning team in two seasons, having gone only 23-20 since Super Bowl XXII and having yet to figure out how to make all the pieces fit against a good team.

"The biggest thing about these last five weeks is we're going to know where this team stands when this is over with," Gibbs said. "We're going to play three division leaders and measure ourselves against darn good football teams. I think we'll all be able to sit down when this is over and say, 'This is where we are.' We'll know we weren't good enough to do it, or be able to say we had a fantastic finish against good teams."

The Redskins are 24-7 in December since Gibbs arrived and this stretch run could be one of their toughest, beginning with home games against the Dolphins and Chicago Bears.

Gibbs said all week he'd like the Dolphins to see RFK at its best, a cold, uncomfortable day with a loud crowd. "It's one of those games where the crowd can make a difference," he said yesterday. "They're a good team and we're going to need the crowd."

One of their challenges today will be scoring against a defense that has allowed only 11.1 points per game and sacked quarterbacks 36 times. The Dolphins are not only good, they're young.

After going 30-33 the last four seasons, Shula has rebuilt with a pair of outstanding drafts and a series of personnel moves, the best of which was trading for unhappy San Francisco cornerback Tim McKyer.

McKyer has teamed with former Maryland star J.D. Brown, a 12th-round choice in 1989, to give the Dolphins two outstanding cover men, and they, in turn, have allowed the linebackers and front four more freedom to rush the passer. The Dolphins have five new defensive starters in all and are the only NFL team that hasn't allowed any individual to rush for 100 yards, pass for 300 yards or catch 100 yards in passes.

Offensively, the Dolphins start with quarterback Dan Marino. But unlike previous years they may not end with Marino and his ability to get the ball to Mark Duper and Mark Clayton (who won't play because of a knee injury).

Shula also rebuilt the offensive line, putting a pair of 300-pound rookies (Keith Sims and Richmond Webb) on the left side and no one older than 25 at any of the other three positions.

Those linemen and fullback Tony Paige (DeMatha High, Virginia Tech) are why halfback Sammie Smith has 594 yards and why Marino is throwing only 31 passes a game -- a career low.

The running game has allowed him to gamble less, and he has thrown one interception in his last 136 passes -- the best such streak of his career.

The bad news for the Dolphins is that Paige has been hurt the last two weeks, during which Miami rushed for only 125 yards total. He may play today, but probably won't be 100 percent.

"We're still not running the way people think we are," Marino said. "We've executed better at times, but we didn't run it good last week {in whipping Cleveland} and not at all against the Raiders. We just have to continue to work on it. We're capable of running it pretty decently."

The running game was also a focus for the Redskins' offense this week. They got only 36 yards on 15 carries against Dallas, and Gibbs has promised to stay with it a bit longer this week no matter what.

He also made two personnel changes this week. Ed Simmons is back at right tackle in front of Joe Jacoby and rookie Brian Mitchell will get at least a few turns at running back behind Earnest Byner, who has gotten every carry since the injury to Gerald Riggs three weeks ago.

The running game and everything else would be helped if Mark Rypien has a game like the one two weeks ago against New Orleans when he completed 26 of 38 for 311 yards and four touchdowns.

The Cowboys often dropped seven and eight defenders into pass coverage last week, but Rypien did have some chances and didn't do much with them, completing 26 of 54 for 267 yards, a touchdown and his season's first interception.

"I wasn't as sharp as I had been against the Saints," he said. "I just didn't throw the ball as well, and I don't know the reason."

The Dolphins and Redskins bring a bit of history into the game. The Dolphins lead the NFL with 198 victories since the 1970 merger; the Redskins are second with 188. Shula, the game's winningest active coach, is trying for his 295th victory. He won his first in the Kennedy administration and has been a head coach every year since. Gibbs led NFL coaches in wins in the '80s.

The Dolphins have won the last four regular season games with the Redskins, and the teams have met twice in the Super Bowl -- the Dolphins winning in January 1973, the Redskins in 1983.

"People in my business don't hold anyone in higher esteem than Don Shula," Gibbs said. "He sort of sets a standard for all of us, and when you think about the success he's had year in and year out, it's kind of mind-boggling."