TUSCALOOSA, Ala. - Alabama has the nation's top pass defense and ranks second overall. No team in major college football allows fewer points than No. 2 Auburn.

Welcome to this year's edition of the Iron Bow, which is sure to be a defensive struggle.

Saturday's game at Bryant-Denny Stadium will feature two of the best defenses around, units built on speed, sound fundamentals and simply making more big plays than they allow.

"This will probably be one of the best defenses, if not the best, defense we'll see, no matter how many games we have left or who we play," Auburn coach Tommy Tuberville said.

"I think it's the fastest defense we've seen all year," Alabama offensive coordinator Dave Rader said of the Tigers.

Alabama (6-4, 3-4 Southeastern Conference) is allowing just 230 total yards per game and has given up just eight passing touchdowns.

Clearly, Alabama defensive coordinator Joe Kines knew what he was doing despite criticism for an inconsistent group last season.

"Joe Kines took a lot of ridicule last year and obviously has made a lot of people look silly," said Tuberville, a longtime friend of Kines.

The Tigers (10-0, 7-0) are allowing just 9.3 points per game, fewest in the nation, and rank fifth in total defense, eighth against the pass and 12th against the run. Plus, they've allowed a single touchdown on the ground heading into a matchup against the league's top rushing offense.

"They run to the football and tackle," Rader said. "They play well and if somebody makes a mistake, they make up for them and somebody's there to make the tackle. They swarm to the football very well. It's quite impressive."

The Tigers are led by the league's top pass rush, an undersized but quick and athletic linebacking corps and a secondary directed by safety Junior Rosegreen and cornerback Carlos Rogers, one of five finalists for the award given to the nation's top defensive player.

"They play lights-out football," Alabama offensive tackle Wesley Britt said. "They run around and they hustle and they never quit."

Alabama's defense is led by a deep group of linebackers that Auburn offensive coordinator Al Borges said is "as good as any we've seen."

Tide safety Charlie Peprah said the biggest difference from last year's group is "the attitude of the guys." He said watching film from last year's Iron Bowl showed a tendency to have one or two players out of position, leading to big plays by the offense.

"We're just running the stuff better and we're practicing to get better, not just to get through it and go home," Peprah said. "We take the initiative ourselves to try to be perfect. That's a big difference."

The defenses will face vastly different challenges Saturday.

Auburn boasts the league's top scoring offense, a diverse attack built around tailbacks Ronnie Brown and Carnell Williams and quarterback Jason Campbell.

"It may be the best offense I've seen on tape in the last 15 years," Kines said. "If you sat down and you wrote a list of things you'd like to have offensively to be successful, they've pretty much got the whole list covered."

The Tide mostly rides the relentless running of Kenneth Darby, the league's No. 2 rusher. Auburn defensive coordinator Gene Chizik said Alabama is "definitely the best rushing team" the Tigers have faced this year.

"Darby is a super football player," said Chizik, whose defense hasn't allowed a team to reach 150 yards rushing this season.

"The offensive line is big and physical and they're running on everybody," he said. "They run the ball well for a reason."