Good luck has been part of the Washington Redskins' success this season. When Matt Stevens lines up at free safety Sunday against the Buffalo Bills at Redskins Stadium, it will be the first time this season the team has changed its starting offense or defense because of an injury.

Leomont Evans, the usual starter, suffered a concussion during last Sunday's win over the Chicago Bears. So the Redskins will turn to Stevens, who has rebounded from a calamitous mistake in the season-opening loss to the Dallas Cowboys to demonstrate a knack for making big plays.

He entered this season with three interceptions in a three-year NFL career with the Bills, Philadelphia Eagles and Redskins. Now, with the Redskins (5-2) about to arrive at the midway point of their season, he's tied with rookie cornerback Champ Bailey for the team lead and for second place in the NFL with four interceptions.

He had two interceptions after taking over for Evans in the Redskins' 48-22 victory over the Bears. Earlier, he tackled Bears running back Curtis Enis for a four-yard loss on a fourth-and-one play from the Redskins' 22-yard line on Chicago's second possession of the game. He also received a game ball for his special-teams play against the Bears. The previous Sunday at Dallas, Stevens recovered a fumble.

If he is impressed by his play this season or overjoyed by the attention he suddenly is receiving, though, he isn't showing it. With his locker surrounded by reporters yesterday at Redskin Park, Stevens shrugged his shoulders and said: "I've been in the right place at the right time."

Stevens's football career always has been an uphill climb. He was born and grew up in Chapel Hill, N.C., but wasn't offered a scholarship by the University of North Carolina or any other major colleges. Instead, he went from walk-on to two-time all-American at Appalachian State.

He was a third-round draft choice by the Bills in 1996, but was waived in August 1997 around the time he began serving a one-month suspension by the NFL for testing positive for steroids. He spent the remainder of the '97 season and the first half of the '98 season with the Eagles, then was claimed by the Redskins off waivers last December.

He was one of the major culprits in the Redskins' 41-35 overtime loss to the Cowboys in the season opener. Stevens, playing because Evans was suffering from muscle cramps in his leg, was fooled badly by a play-action fake, and Cowboys wide receiver Raghib Ismail sailed past him to make the game-winning touchdown catch. In this season of accountability at Redskin Park, Stevens could not be assured of having a job the following week. But he did, and he has taken advantage of his opportunities since the Ismail play.

"It got me down," Stevens said. "Obviously it was a hard play. But it was only the first game. You still have 15 to go. If they lose confidence in me, they lose confidence in me. I would go somewhere else. But I didn't think that would happen."

He will get plenty of playing time against his former team because Evans was told by doctors not to resume playing before next week. Evans said yesterday he hopes to return to practice by the middle of next week and play in the Redskins' game at Philadelphia in 10 days.

The Redskins have the NFL's last-ranked defense, but they say they've been encouraged by how they've played in two of their past three games--wins over the Arizona Cardinals and the Bears, sandwiched around their second loss of the season to the Cowboys. The Bears amassed 445 yards of offense last Sunday, but didn't manage any points until after the Redskins had taken a 45-0 lead in the third quarter.

"I think we're definitely taking steps in the right direction," defensive tackle Dan Wilkinson said yesterday. "Are we satisfied? Are we where we need to be? No, but I think we're getting better."

The Bills (5-3) almost certainly are the best team the Redskins will face in a seven-week stretch that began with the Chicago game. But Buffalo Coach Wade Phillips said yesterday that quarterback Doug Flutie's top receiving threat, wideout Eric Moulds, probably will remain sidelined by a hamstring injury. In the past three games, Flutie has thrown eight interceptions while the Bills have totaled only 43 points and gone 1-2. Flutie has thrown 11 interceptions this season to go with 10 touchdown passes.

Still, the diminutive quarterback's elusiveness makes him difficult to defend. He scrambled for 17 yards on a fourth-and-15 play during Buffalo's winning touchdown drive in last Sunday's 13-10 triumph at Baltimore, and he has 307 rushing yards this season.

"It's going to be something else chasing this guy," Wilkinson said. "He's not just little. He's fast. He has a lot of body leverage. He can keep his feet. He has a very big heart and a big-time will to win."

Wilkinson said the Redskins defenders must be disciplined, but can't allow their wariness of Flutie's improvisational skills to rob them of their aggressiveness.

"As a defensive line, we have to stay levelheaded," Wilkinson said. "We can't get frustrated or upset if we miss him. We can't let him dictate the way we rush. We have to be sound and disciplined, but we also want to be relentless. We don't want to be hesitant."