The Washington Redskins have been on a month-long rush: four consecutive victories and 18 quarterback sacks.

The problem is, injury has rushed up on the Redskins. Yesterday, Coach Joe Gibbs said defensive end Dexter Manley, the team's best pass rusher, who sprained an ankle in the team's five-sack, 35-7 victory over Indianapolis Sunday, is "on crutches and looks doubtful" for Sunday's game at RFK Stadium against the Dallas Cowboys, the team Manley loves to sack the most.

Furthermore, Gibbs said, all-pro wide receiver Charlie Brown, who missed the Colts game with a sprained ankle, is "doubtful" for the game that will decide sole possession of first place in the NFC Eastern Division.

Gibbs said Manley likely would be replaced on running downs by recently acquired Tom Beasley and on passing downs by veteran Tony McGee. Brown again would be replaced by Mark McGrath, who against the Colts caught a career-high seven passes for 82 yards and scored his first touchdown. The receivers coach, Charley Taylor, yesterday termed McGrath's performance against the Colts "a perfect game. Mark's a tough little rascal."

These days, the Redskins' injury list is more like an injury scroll: it's painfully long. Kick returner Mike Nelms sprained an ankle, catching his foot in the Hoosier Dome's artificial turf, and is "day-to-day," Gibbs said. Both strong safety Tony Peters (abdominal muscle pull) and right tackle George Starke (fluid drained from a knee) did not play against the Colts, but will return to practice Wednesday and should be healthy enough to play against Dallas, Gibbs said.

Against the Colts, Peters was replaced by Ken Coffey, the former starter who recently was reactivated from the injured reserve list. Asked if Coffey might start again this week, Gibbs said, "You'd have to ask Richie."

The defensive coach, Richie Petitbon, said of the Peters-Coffey question, "I don't know."

Petitbon did say "Kenny played well" against the Colts. Several members of the Redskins' defense have said privately they feel Peters may have been benched against the Colts, not so much because of injury but because of ineffective play. They admit it's a difficult thing to read.

Peters, 31, a former all-pro who had never missed a game in his previous eight professional seasons, said last week that, because of the injury, "I don't have the bursts (of speed) I really want and I rely so much on quickness and speed."

Petitbon was miffed when the subject of Peters' "benching" was raised. Sternly, he said, "The kid's got a muscle pull. He has not been benched."

Also, linebacker Rich Milot, who had a bone chip removed from his elbow 16 days ago and has missed the last two games, will begin practicing lightly Wednesday, in seven-on-seven passing drills. However, it seems unlikely he will be ready to play against the Cowboys.

"It's really hard to tell what the plan is now," said Milot, the team's only linebacker to play on all downs. "I know that I don't plan on doing anything stupid that will set me back a few more weeks. I think it will be a situation (Sunday) where, if I'm really needed, I'll be there." In Milot's absence, Monte Coleman has shifted from a being a passing-down specialist on the left side to a full-time linebacker on Milot's right side.

After the Redskins had lowered the boom on the Colts, fullback John Riggins said, "I don't think it's any secret that our strength is in the lines."

The offensive line overpowered the Colts, allowing quarterback Joe Theismann time to complete 17 of 20 pases for 267 yards and four touchdowns -- he was sacked once -- and allowing Riggins to run for 94 yards on 19 carries. Riggins, who carried the ball just once in the second half, now is just 24 yards short of becoming the fifth NFL player to run for 10,000 yards.

Offensive tackle Mark May said Riggins could have "run for about 200" if he had played the entire game. Riggins said his absence in the second half was "mandatory more than anything" and noted that his lower back pains caused him to hurt "from the navel to the kneecaps."

"Our offense is getting close to what we've been in the past," May said.

Which brings us to the defensive linemen, a unit that likes to fancy itself as "The Silent Force." In the season's first two games -- losses to Miami (35-17) and to San Francisco (37-31) -- they were quite silent, netting just two sacks. They said Miami's Dan Marino had a quick release and San Francisco's Joe Montana was plain tough to catch.

Times have changed.Count the quarterback dustings over the last four weeks: the Giants' Phil Simms was sacked five times, the Patriots' Tony Eason four times, the Eagles' Ron Jaworski four times and the Colts' Mike Pagel and Art Schlichter five times.

"I remember we piled in on the quarterback on one play," Dave Butz, the Redskins' all-pro defensive tackle, recalled yesterday of the woe inflicted upon Pagel. "Darryl Grant hit him, then Dexter (Manley) hit him and then somebody else, I think it was (end) Tony McGee, hit him. I just rolled over the pile and (Pagel) said, "There's a lot of beef here.""

The defensive line coach, Torgy Torgeson, said of the play, "All four lineman and all fuor linebackers came in like a torrent. Everybody beat their guy clean. It's what we like to see."

"I think our front four has been playing excellent. That will hurt us without Dexter. Dexter was having a great year," said Gibbs. Manley is tied with the oft-blitzing Coleman for the team lead with five sacks each.

"The numbers are certainly improving," said Petitbon, comparing the season's first two weeks (in which the defense gave up an average of 36 points per game, with two sacks and zero interceptions) to the last four weeks (in which the defense gave up an average of 7.7 points, with the 18 sacks and six interceptions, all the latter by rejuvenated cornerback Vernon Dean).

Critics point out that the Giants, Patriots, Eagles and Colts are hardly among the league's superior teams. However, the combined record of these four teams (not including their four losses to the Redskins) is 11-8.

Said Butz, "The Colts had the No. 2 rushing offense in the league, didn't they?The Giants were off to a heck of a start (2-0) when we played them, weren't they? The Patriots had one of the league's top (then No. 2) rushing games, too, didn't they?

"From the second half of the San Francisco game to now, instead of having one or two guys swarming the ball, we have 10 or 11."