The Washington Redskins' emotions energize when they know Tom Landry is coming to town.

So, cool as silver, Redskins running back John Riggins walked into the Redskin Park media room yesterday, sat down for his second press conference of the year and said, "Well, I come to bury the Cowboys, not to praise them. So let's get those shovels out."

Asked about recent remarks by Dallas Coach Landry implying the Redskins had won last year's Super Bowl without vast talent, Riggins said, smiling, "I guess if I had all that talent (of Dallas) and didn't win the Super Bowl, I'd feel the same way. Alleged talent, I might add. . . .

"I really don't think it's good for a team to get tunnel vision for one team. There are a lot of teams that can play with Dallas now," Riggins added. "There are no great football teams anymore, except maybe Nebraska. And they are not on our schedule."

Dallas-induced emotion did stand aside yesterday long enough for the Redskins to make one roster move. They placed offensive tackle/guard Don Laster on the injured reserve list (for a minimum of four weeks) because of a sprained neck. The Redskins filled Laster's spot by claiming second-year cornerback Brian Carpenter, waived Monday by the New York Giants and last season by Dallas.

Carpenter becomes the Redskins' fourth cornerback. "We wanted to try to get back someone we had," Coach Joe Gibbs said, most likely referring to rookie cornerback Greg Jones, released Monday, "or find someone we thought was better."

Riggins' press conference was not as long or humorous as his training camp session. "I'm feeling dull today," Riggins said. Rolling his eyes mischievously, he said without elaboration, "That probably has to do with last night."

If Riggins' mood represented silver, than certainly wide receiver Art Monk's mood represented blue.

Monk suffered a sprained knee ligament against Cincinnati Aug. 12. He will not play against the Dallas Cowboys Monday night at RFK Stadium. He might not play at Philadelphia the following week, either.

"We really don't know when he's coming back," Gibbs said. "It's wait and see."

"Evidently, the sprain is worse than we thought originally," said trainer Bubba Tyer. Monk was supposed to be back in 10 days to three weeks. "This is the third week," Tyer said, "and he's progressing slowly."

Normally a quiet man, Monk has become sullen and silent. He's working hard on rehabilitation, Redskins officials say, doing leg exercises and even jogging in a swimming pool, allowing his knee to rebuild slowly.

Late yesterday afternoon, Monk stood alone in the Redskin Park locker room. "Looney Tunes" cartoons were on the television behind him, but Monk was not laughing. His teammates were out practicing. He was alone. Smurfs Virgil Seay and Alvin Garrett have taken his playing time, for now. This is why Monk has become silent.

"It's just a different feeling than last year," Monk began. That's when Monk broke a bone in his right foot in the final regular-season game against St. Louis and missed the playoffs and the Super Bowl. He had played in 41 consecutive games before his injury. Furthermore, he had never missed a game or even a practice because of an injury in his four years at Syracuse.

"It's just different now--I don't know how to say it," Monk said. He paused for a moment. Then, the sullen look again overtook his face. "I really don't want to talk about it," he said. He walked away.

"I ask Art how the leg is coming along and he just says, 'Slow,' " said wide receiver Charlie Brown. "It's a sad feeling. But it's part of life, football life, I guess.

"Art didn't get to play against Dallas last year (in the NFC title game) because he was hurt. Now, it's time to play Dallas and he's hurt again. I know he wants to play bad. It's got to bother him."

In his rookie season of 1980, Monk caught 58 passes for 797 yards. In 1981, he caught 56 passes for 894 yards. In nine games last year, he caught 35 for 447 yards.

Now, the Dallas opener is only five days away. Pictures of Cowboys stars like Danny White, Randy White, Harvey Martin and John Dutton--all torn out of the Cowboys media guide--stare at the Redskins from the locker room bulletin board.

Yesterday, the Redskins began their strategic preparation. "For them," Riggins said of Dallas, "they got beat in the championship game. So they are probably looking forward to this game more than the Redskins.

"I get the feeling (people think) we kind of snuck up on the Super Bowl," Riggins said, "that we just happened to be there at that moment. I don't know, maybe that's true. I think we've got a good football team, not a great one.

"I don't think we're looked up to. Maybe we're even looked down at. I guess we're the champion in sheep's clothing."

Closing his pregame book on the Cowboys, Riggins said, "I've always said this over the years: the best thing about Dallas is their uniforms. If you put the players in New Orleans' uniforms, they might not win many games. I'm just saying they have the tradition."