With the Dallas Cowboys needing a first down to run out the clock in the final minutes Monday night, nursing a 13-7 lead and facing third and 18, Washington Redskins cornerback Walt Harris tackled tight end Jason Witten five yards short, forcing a punt. With the Cowboys trailing, 14-13, about a minute later, and driving toward a game-winning field goal attempt, Harris dropped wide receiver Terry Glenn one yard shy of a critical fourth down conversion, preserving Washington's wild comeback victory.

All the while, middle linebacker Lemar Marshall was hustling around the field, directing the defense and willing himself through a groin injury. Every movement triggered a piercing shot of pain, but he remained focused on making the correct defensive calls, relaying information to his teammates and picking up the proper signals from the coaches on the sideline. The Redskins, who have a bye this weekend, likely would not be 2-0 without the contributions of Harris and Marshall.

When stalwart cornerback Fred Smoot and middle linebacker Antonio Pierce departed this offseason via free agency, many wondered if Washington's third-ranked defense would take a precipitous drop. Instead, the unit has been as stout as ever -- conceding just 20 points through two games, and only one long scoring drive -- with Harris and Marshall shining.

"Walt is doing a good job, man," cornerback Shawn Springs said. "Everybody was talking about Smoot leaving, but Walt is performing, making some great open-field tackles and getting work over there and just getting the job done. And Lemar played 16 games last year with [linebacker] LaVar [Arrington] going down early, so they're stepping up. Those guys are really stepping up. That's what we talk about being in Gregg Williams's defense -- everybody is a starter, and if I go down somebody else will step up, and if [Pro Bowl linebacker] Marcus Washington goes down, then somebody else will step up. That's just how it is."

Harris was seemingly everywhere against Dallas, diving headfirst to upend bullish running back Julius Jones, defending passes well downfield, negating receivers in the slot. The only significant pass Dallas completed -- a 70-yard flea flicker -- occurred on the opposite side of the field. He made plays in the backfield and was second on the team with seven tackles, earning the Redskins' defensive player of the week honor. It was reward for a franchise that took a gamble on Harris, 31, as a free agent in 2004 -- signing him despite 50-50 odds of being able to return from career-threatening knee surgery -- and had the faith to make him a full-time starter when Smoot left for Minnesota.

Monday, it seemed as if wherever Harris went, the ball followed, whether on the ground or in the air.

"Yeah, those kinds of things happen for some reason," Harris said, "and you're just around the ball a lot. It's fun to be in a position like that to be able to make plays."

Harris was never 100 percent last season, but still thrived as a nickel back. But he has started most of his NFL career, and is getting back to peak form. "That tackle on fourth down was a huge play," said defensive coordinator Greg Blache, who coached Harris in Chicago, "and he played like Walt can play. It was nothing out of the ordinary. What you saw last year was just glimpses with Walt coming off of that injury. Now that he's healthy and he's playing, he's a big part of it."

Marshall, 28, had never started a game before last season, but he filled in exceptionally on the weak side for Arrington, a three-time Pro Bowler, in 2004, and was converted to middle linebacker, a huge transition. He must have a deeper knowledge of the entire defense, work quickly to keep his teammates aligned and fill a vital role in the middle of the field. So far, he has met the challenge well.

"It's a complete switch for him," said linebackers coach Dale Lindsey, who issues compliments begrudgingly, "and he's had to learn everything in the last seven weeks, so I think he's doing pretty well under the circumstances. He's done a good job getting his line set, and been very productive."

Marshall, who debated pulling himself out of Monday's game but expects to play Oct. 2 against Seattle, is learning to be more vocal on the field, and spends considerable time at home studying his defense and opposing offenses. He has to be the smartest player on the field, and takes that responsibility seriously.

"I definitely do more of that homework," Marshall said, "just because you don't want to let yourself down, let your teammates down, let the coaches down, or let the Washington Redskins down. So I find myself doing more studying, and I never had people who broke things down the way these coaches do, and you understand the game a lot more. You have to make sure you're on top of it, and that's what I try to do -- stay on top of it, be ready for adversity and be ready to adapt if something new comes up."

Cornerback Walt Harris has become a full-time starter after the departure of Fred Smoot to Minnesota. Washington's defense has allowed 20 points through 2 games.