EASTON, PA., AUG. 8 -- Washington Redskins defensive end Dexter Manley suffered a partial tear of the medial collateral ligament in his right knee in a scrimmage with the New York Jets today. Team doctor Charles Jackson said the Pro Bowl defensive end would miss a minimum of "several weeks" of practice and added it was "very difficult to say" whether Manley would be able to play in the team's opening regular season game Sept. 13.

Jackson did not rule out the possibility of arthroscopic surgery for Manley, but said there were no plans for an operation.

"We'll be watching him very closely over the next week to 10 days to determine how he's doing," Jackson said after the scrimmage at Lafayette College, which the Redskins won, 27-18. "If there's a lot of pain or a lot of swelling or if blood collects in the knee, there's a possibility we'd want to examine him more closely."

Jackson said Manley suffered a Grade 2 sprain of the knee ligament, which means it "was not a complete tear." A Grade 1 sprain means no fibers are torn, Jackson said, and a Grade 3 sprain means the ligament is completely torn in two.

"It's a very common injury," Jackson said. "You can't tell to what extent it is {torn}."

Manley, who would not speak to reporters or issue a statement about the injury, also was experiencing "some tenderness" in his ankle, Jackson said. "He took a direct blow and there is tenderness along the outside of his leg. It's painful."

Manley was injured on the sixth play of the scrimmage when, according to a teammate, strong safety Alvin Walton apparently was blocked or fell into him during a tackle of Jets running back Roger Vick, New York's first-round draft pick. Vick gained six yards on the play and was tackled by defensive tackle Darryl Grant.

Manley writhed in pain on the ground at Fisher Field for several moments as teammates tried to comfort him. Five minutes later, after receiving medical attention, he was helped off the field, not putting any weight on his right leg.

Third-year defensive end Steve Hamilton, who started two games in 1986, replaced Manley at right defensive end.

Manley sat on the bench for the rest of the scrimmage, his right leg iced and wrapped from thigh to toe. He reacted with distress as he spoke to Jackson, team trainers and his teammates and coaches.

"When can I play?" he asked Jackson. "When can I play?"

Jackson said Manley specifically asked him about the season opener Sept. 13 at RFK Stadium against the Philadelphia Eagles.

"I said, 'I can't really tell,' " Jackson said. "I simply don't want to promise him and not be able to do it. On the other hand, I don't want to say he can't do it either. It's just very difficult to say . . . We just have to wait and see the next week to 10 days, see how he does, whether or not he's going to have a go {at playing in the regular season opener}."

Jackson said Manley was upset about the injury on the sideline and finally "calmed down" after the scrimmage. Manley limped, with the help of team personnel, from the locker room to the team bus in a thigh-to-toe soft cast.

"With a patient like Dexter, he's very excitable," Jackson said. "He has difficulty in really localizing what's going on. Going out on the field, it's hard to tell whether it's his left leg or his right leg. But he took a blow on the outside of that {right} leg and he was having pain both in his ankle and in his knee."

Jackson, who said he was going to examine Manley again later tonight when the team arrived back at its training camp in Carlisle, Pa., said it was difficult to determine exactly when Manley could return to practice or play in a game. The Redskins' first preseason game is Friday at 8 p.m. against the Pittsburgh Steelers at RFK Stadium.

"It's a matter of how well he does in the early period," Jackson said. "If he has a lot of tenderness and pain and can't put weight on it, we'll just have to go real slow with it. Dexter's going to be one that we're going to have to hold back. He wants to go, so we'll just be very slow and careful with him."

Jackson said he "would hold him back for several weeks," at the least. Asked about the maximum time, Jackson said, "I just can't say."

Redskins Coach Joe Gibbs tried to remain optimistic. He said there was "no question at all" that Manley would be ready to play by Sept. 13.

"It's just a matter of how much it swells and what it looks like tomorrow," Gibbs said. "I think it scared him . . . We'll just have to see how it reacts the next day or so. That will tell us how long it'll be."

Manley's injury depletes the depth of the Washington defensive line and seems to place a premium on the team's signing of veteran defensive tackle Dave Butz, who has entered the second week of a contract dispute.

"I guess we would have to say we are a little thin," said defensive end Charles Mann.

Manley was not the only Redskin to be injured in the scrimmage, played before 8,100. Linebacker Anthony Copeland sprained his left knee and running back Dwight Garner injured his left foot when it got stepped on by another players' cleats. The severity of each injury was not known.

Offensive tackle Mark May (sprained right knee), running back George Rogers (sprained left big toe) and linebacker Kurt Gouveia (broken blood vessel in his forehead) did not participate in the scrimmage.

The Redskins won the scrimmage on the last of their five possessions. Rookie free agent tight end Craig McEwen of Utah caught an 18-yard touchdown pass from quarterback Mark Rypien to break an 18-18 tie. Max Zendejas later kicked a 45-yard field goal to give the Redskins their final margin.

Earlier, incumbent Jess Atkinson missed a 43-yard field goal wide right.

"We're just going to grade them as they go," said Gibbs. "It's Jess' {job} until somebody takes it away from him. If we come out of this with a strong feeling for somebody else, then we'll go that route."

Jay Schroeder completed four of nine passes for 100 yards and one touchdown, a 70-yard pass to wide receiver Gary Clark, who beat cornerback Russell Carter and free safety Harry Hamilton on the play. In earlier seven-on-seven passing drills, Schroeder completed 16 of 20 passes for 194 yards.

Doug Williams completed 10 of 18 passes for 68 yards in the scrimmage. He threw for two touchdowns, a six-yard pass to wide receiver Eric Yarber and a two-yarder to tight end Chris Dressel. Williams was seven of 20 in the seven-on-seven drills for 83 yards.

Rypien completed five of the 10 passes in the scrimmage for 41 yards and McEwen's touchdown. He was 14 of 18 in the earlier drills for 222 yards and three touchdowns, two to rookie tight end Alfred Jenkins and one to free agent wide receiver Carl Williams.

Redskins rookie running back Tim Smith was the leading rusher in the scrimmage with 37 yards in six carries, including a slashing 19-yard run. Clark had four receptions for 100 yards to lead all receivers.