By Jason La CanforaWashington Post Staff WriterTuesday, October 31, 2006The Washington Redskins were without four of their premier offensive players for much of yesterday's practice because of injuries -- quarterback Mark Brunell, tailback Clinton Portis and wide receivers Santana Moss and Antwaan Randle El -- and starting middle linebacker Lemar Marshall did not practice. With only Brunell certain to practice tomorrow, Coach Joe Gibbs said it is too soon to determine how many will play Sunday against the Dallas Cowboys.Of the group, only Randle El (heel) participated in team drills, shagging punts on special teams, with Brunell (rib muscle) throwing a bit on the side. Portis (left ankle) and Moss (left hamstring) walked gingerly to the field about 20 minutes into practice and did only light individual work. Marshall (left ankle) was on the field but did not take part in drills. Merely trying to run the offense in practice this week would be difficult enough with so many key players out, Gibbs said, and facing the Cowboys without their top players would not bode well for the 2-5 club, which is last in the NFC East after three straight defeats."With that group, we'll just have to see as the week goes," Gibbs said of his injured players.The Redskins return to practice tomorrow, and Brunell, who also sat out last week's abbreviated on-field schedule, said he will be able to participate fully. Reserve quarterback Jason Campbell took much of the work last week, a first for the 2005 first-round pick, and Gibbs said that Campbell and veteran backup Todd Collins each worked with the first team yesterday. Gibbs said that the rotation for Sunday's game remains unchanged, with Brunell the starter, Collins No. 2 and Campbell designated the third quarterback.When the Redskins' offense has moved the ball this season, Portis has been the fulcrum. He missed the first game against Dallas -- a 27-10 defeat in Week 2 -- and overcame shoulder injuries from the preseason to lead the attack in consecutive victories over Houston and Jacksonville, but carried only 26 times the past two games. Should Portis be unable to play, Gibbs said he is confident in the other backs, including T.J. Duckett, who has carried just five times, all in the first game against Dallas."It's all right. It's coming around," Portis said. "I'm out of the cast. I did a little work moving around laterally, just seeing how it feels. It feels okay. I'm sure we'll do a little more on Wednesday having an extra day [of practice] this week. Today, I didn't try a lot. We'll come out and see what I can do on Wednesday and go from there."