ATLANTA — The New Orleans Saints are chasing perfection.The Atlanta Falcons are just trying to survive.While the Saints (12-0) have already clinched the NFC South title and merely need a win or tie Sunday at the Georgia Dome to ensure they'll have a first-round bye and at least one playoff game in the Big Easy, the Falcons' hopes of making it back to the playoffs are looking bleaker by the week.Atlanta (6-6) has lost five of its last seven and shows no signs of pulling out of the tailspin, not with a rash of injuries that have hit especially hard on the offensive side.Last week, the Falcons were without five starters — nearly half the offense — when they faced the Philadelphia Eagles in a crucial NFC game. Not surprisingly, they were blown out at home, 34-7."We can't afford another loss," receiver Roddy White said. "We've got to find a way to win this game."The Saints have found a way to win every game so far, making them just the eighth team in NFL history to start the season 12-0. Another win will set a franchise record and lock up that bye, but New Orleans has bigger goals in mind.Like beating out Minnesota (10-2) for top seed in the NFC, which would ensure the Saints of nothing but home games throughout the conference playoffs. That would put them in the best possible position to reach the Super Bowl for the first time in franchise history, the perfect antidote for a city still struggling to bounce back from Hurricane Katrina."It was exciting before, but now it's really exciting, because each week now holds another prize at the end of it," quarterback Drew Brees said. "You win this week, you secure a first-round bye. Maybe the next week or the week after you secure potentially the one seed and then potentially the week after that you have an opportunity to make history (at 16-0) and you're in the playoffs, so it gets more and more exciting each and every week."The Falcons would love to end New Orleans' quest for an unbeaten season, but it's hard to see them doing it without Matt Ryan or Michael Turner."That's like 65 percent of our offense," White said.Actually, he's a little off. Those two have been in on more than 80 percent of the total yards.Ryan, the second-year quarterback, missed last week with a turf toe injury and seemed highly unlikely to play against the Saints. Turner, the NFL's season-leading rusher in 2008, has been struggling with a high ankle sprain for nearly a month and the injury flared up again when he came back two weeks ago.Against the Eagles, the Falcons were missing those two, as well as receiver Michael Jenkins and starting linemen Harvey Dahl and Sam Baker. At least some of the wounded are likely to return Sunday, but now cornerback Chris Houston is down with a hamstring injury, weakening an already suspect secondary."The next guy has to step in and keep it rolling," linebacker Mike Peterson said, trying to put a positive spin on the grim injury report. "This is not like high school or college. You can't just throw in the season because you've had a few injuries. You expect the second team and the third team to step in. Of course, they're not going to perform like the starters or they would be starters. But we expect them to come in and get the job done."The Falcons didn't get it done a week ago. In the return of Michael Vick to the Georgia Dome, the Eagles romped to an easy win that not only put a serious dent in Atlanta's playoff hopes, but moved the home team another step closer to extending one of the NFL's most infamous streaks.This is a franchise that has never had back-to-back winning seasons in its 44-year history. If the Falcons lose again Sunday, they'll need to win out (or at least get two wins and a tie) to avoid a .500 or worse finish.New Orleans has struggled through much of its existence, as well, but the Saints are really on a roll this season. The Brees-led offense is lighting up the league, ranking third in yards passing, fifth in rushing and first overall. This week, the Saints go against a defense that ranks near the bottom in all three categories.Brees downplayed the obvious advantages."The fact is we're going on the road, playing a team that's only lost two games at home in the last two years," he said. "They would love nothing more than to knock us off."Atlanta's defense looks ripe for the picking, as in picking apart — especially in the secondary. The two guys who started the season as the No. 1 cornerbacks, Houston and Brian Williams, are both out with injuries. The Saints have scored more than 40 points in four games and haven't been held below 24 all season.When Falcons coach Mike Smith studies New Orleans on film, he sees a unit that is playing as well as such prolific offenses as the New England Patriots two seasons ago or the 1998 Minnesota Vikings."They're operating very, very well," Smith said. "Not only throwing the ball, but running it, too."Peterson said he looks forward to the challenge, even with the Falcons coming off their most lopsided loss of the season."I like playing against the best," he said. "They're throwing the ball so well. Anytime you throw the ball well, it opens up the run game. Teams are so focused on stopping the pass, stopping the pass, they're able to pop some runs. They've got a great mix of run and pass."