Every time the New York Giants talked optimistically this week about beating the Redskins, Washington's Joe Gibbs grew more pleased. He didn't have to look any further to find material for his pregame speech today.

But the Giants were just being straightforward. If their most recent rebuilding program, now in its third year under Ray Perkins, can't beat Gibbs' newly restructured team, then what opponent can New York handle this season?

Yet the Redskins, who are 6 1/2-point favorites, also like their chances of defeating the Giants, even if Gibbs prefers not to make a prediction about this 1 p.m. game in RFK Stadium (WDVM-TV-9).

"We should play better this week than we did against Dallas," linebacker Neal Olkewicz said. "And if we do, we should win. I'm sure they think the same thing. Neither one of us are superpowers, they aren't Dallas and we aren't Philadelphia. They'll play with similiar abilities.

"But they don't do a lot of the tricky things the Cowboys use. They are more of a straight team, and we do better matched up against that type of style."

Gibbs does venture that this is a crucial game for his team, since the Redskins don't want to start the season losing two in a row at home, especially to division opponents. Besides, they beat New York twice last year and a defeat in RFK would be a backward step.

Despite Gibbs' attempts to portray the Giants as an opponent that should have beaten Philadelphia last week instead of losing, 28-7, New York is struggling. Its offensive line is average and hindered by injuries. Its running backs hardly are all-pros and its defensive line is starting a rookie nose guard. Only punter Dave Jennings and an impressive group of linebackers stand out.

But the Redskins didn't show much better against Dallas. Their defensive line had a horrible afternoon and is sure to be tested frequently today. Quarterback Joe Theismann couldn't stop throwing interceptions, finishing with four, and a much-heralded running attack was neglected in the face of 49 passes.

"I'm going to improve," said Theismann, who will be playing with a sore thumb. "Every day I'm getting more comfortable in this offense. I made some bad reads last week but we still came awfully close to doing very well."

Gibbs seems certain to order more running plays this week, if for no other reason than this is the Giants' defense, not the Cowboys'. Philadelphia pounded away for 178 yards on the ground last week, even though starting fullback Leroy Harris is injured.

More reliance on Joe Washington, John Riggins and friends also may help solve another troublesome area. Since early in training camp, the Redskins have become mistake- prone when they move inside the 30, frequently because of an impatience to score quickly.

"It's a major problem and we have to do a better job at it," Gibbs said. "We've put extra emphasis this week. We can't mess up scoring opportunities."

Theismann will be throwing into a so-so secondary that may feature a new starter, strong safety Bill Currier. But the Redskin quarterback will be trying to avoid the linebackers as much as possible, especially veteran Brad Van Pelt and Lawrence Taylor, the North Carolina rookie who has been impressive.

"I'm sure the Giants are going to go after us on the ground right away," Olkewicz said. "They always try to run on us, but this time they'd be crazy not to." The Redskins gave up 206 rushing yards to Dallas.

Giant runners Billy Taylor, Leon Perry, Doug Kotar and Bo Matthews gained just 55 yards against Philadelphia. But the Eagles weren't playing Mel Kaufman, a rookie free agent, at starting linebacker either. Kaufman will replace Rich Milot, who has a sore shoulder.

With Brad Benson, the starting left tackle, and his backup, Jeff Weston, both hobbled, ex-Redskin Tim Stokes, just picked up this week off waivers, could be asked to block defensive end Coy Bacon, the Redskins' best pass rusher.

A good game by Bacon, who still might be capable of taking advantage of this mismatch against Stokes, could perk up a lethargic pass rush that sacked Danny White just once. The Eagles got to quarterback Phil Simms six times last week with the help of blitzes, a tactic Richie Petitbon, the Redskin defensive coordinator, loves to employ. If Simms is harassed, the Washington secondary would be helped trying to cover speedy receiver Earnest Gray.

"We are just trying to hang on for the next three weeks and not get anyone else hurt," said Petitbon about his defense. "We can't afford to lose anyone else before we can bring back Wilbur Young and Brad Dusek. But we'll play better this week, we'll be more forceful.

"We just have to force some turnovers, make some big plays. We didn't have an interception last week. If we are going to be successful, we have to cause mistakes. We can't stand in there and pound it out."

With only two true defensive tackles, Petitbon has used both Bacon and end Karl Lorch inside at practice this week. He's also given newcomer Mike Clark, the defensive end signed on Monday, plenty of early work at Bacon's outside position.""We are still searching for answers to a lot of questions," Gibbs said. "We are still finding out a lot about our players, who will come through in pressure situations, who will respond after becoming tired, that type of thing. But I expect improvement from last week. That's the one encouraging thing about a young team, it usually does get better fast."