Washington Redskins running back Gerald Riggs did not practice yesterday because of muscle spasms in his back, but he is still expected to play in Sunday's game against the NFC East-leading New York Giants at RFK Stadium.

Riggs, who did not complete Thursday's practice because his back began tightening, was examined yesterday morning by team physician Charles Jackson. X-rays were negative, and Jackson found nothing wrong with the joint spaces or vertebrae in Riggs's back, trainer Bubba Tyer said. Thus, Tyer said it is believed Riggs's problem is strictly muscular and will not prevent him from playing Sunday.

Coach Joe Gibbs was similarly optimistic about Riggs's condition, but he expressed a hint of caution.

"I think he'll be okay, but we'll just see," Gibbs said. "We kept him out of things today because we wanted him to rest up . . . I'd say right now he'll be ready to go" Sunday.

Riggs took therapy yesterday, then came outside about halfway through practice, dressed in sweatpants and a windbreaker. He declined to comment.

"Everything is normal and looks good," Tyer said, "but he's got a bit of muscle spasm and soreness in his mid-back. It's really not that bad, but we didn't want to make it worse by having him practice today."

If Riggs cannot play Sunday, running backs coach Don Breaux said Earnest Byner "just continues to go." Rookie Brian Mitchell took Riggs's place in practice yesterday.

"It's like Coach always tells me," Mitchell said, " 'Just be ready because you don't know what's going to happen.' If {Riggs} can't go, I have to be ready to go.

"I don't get many reps, but they always tell you to get mental reps. So, I know what to do. It's just a matter of getting in there and doing some things. I don't think it would take much work because I've run all the plays we have, and I'm very familiar with everything they expect the running backs to do. I don't think it would be a real problem."

Riggs, who will turn 30 in early November, had his best game of the season against the Phoenix Cardinals two weeks ago. Washington was off last week. He carried the ball 19 times for 95 yards and a touchdown. Riggs's total was the team-best this season and the most he has gained since Week 7 last season, when he gained 99 on 27 carries against the Tampa Bay Buccaneers.

"He's played physically, he's had a real good attitude and he's worked very hard in practice," Breaux said. "You couldn't ask for anything better really."

The same was the case for the first seven weeks of last season, during which Riggs totaled 658 rushing yards -- 202 in Washington's two games against the Giants. Since Riggs rushed for 91 yards against the Giants in Week 6 last season, no one has rushed for more against them. Riggs's 111-yard effort against the Giants in the season opener last year was the only time anyone has reached the 100-yard mark against them since the Rams' Greg Bell ran for 112 in Week 4 of the 1988 season.

But Riggs's final nine weeks last season were interrupted by injuries, mainly a sprained arch. And because the Redskins won their final five games with Byner as their primary running back, Breaux said, that's they way they began this season.

"We said going into the year that Earnest was going to start," Breaux said. "I think that was fair, and I think Gerald would concur with that."

It also probably did not help matters that Riggs spent a sizable portion of his offseason working out at his alma mater, Arizona State University, rather than at Redskin Park, as Gibbs prefers. But the Redskins could not argue with the results.

"He was in better shape this year than he was the year before," Breaux said. "He said he was going to come to camp in shape and he did what he said he was going to do. It was obvious from the first day of training camp that he had worked."

But Riggs's work did not pay off very much.

"The running game was working," Byner said, "but we weren't running the ball enough to say we had a running game. There really wasn't any difference in the alternation against Phoenix. It's just that we ran the ball more."

Said Breaux: "When you're making first downs and you're maintaining possession of the ball, you're going to be able to run more of your offense. As a result, Gerald was able to play more against the Cardinals. . . . I think we have two proven talents there, and I know in the course of an NFL season, we're going to need both of them."

Redskins Notes: With Washington's last four games against the Giants having been decided by a total of 14 points, Redskins kicker Chip Lohmiller said he knows Sunday's game may come down to him and counterpart Matt Bahr.

In the teams' first meeting last season, Raul Allegre made a 52-yard field goal with six seconds left to give the Giants a 27-24 victory. And in their second meeting in 1988, Lohmiller missed an extra point early in the game and a 36-yard field goal with 2:54 to play in the Giants' 24-23 victory.

"This is the kind of game that is always a close game, so you know that time may come up when time is running out and I may have to go out there and kick the winning field goal," Lohmiller said. "The last couple of weeks I've been mentally preparing myself for that."

Despite the 1988 game, Lohmiller said he does not carry a grudge toward the Giants. "I don't like to look back at misses," he said. "I'd rather look back at the wins. Maybe I could get a shot like I did against Philadelphia" late in 1988, when he kicked a 44-yard field goal with one second left to give Washington a 20-19 victory.