One of the most exciting things for football fans is the opportunity to watch two great players face off. No small amount of hype preceded this week’s Monday night game, when two of the best wide receivers of this generation – Philadelphia’s Terrell Owens and Minnesota’s Randy Moss – took the field at the same time. Each caught a touchdown pass in the fourth quarter, but neither was the primary focus of their team’s offense.

That’s why a match up of great quarterbacks can be so much more interesting: each man plays a larger role in his team’s fate. History has given us some great quarterback rivalries: Hall of Famers Joe Namath and Bob Griese faced each other in 15 games between 1967 and 1976. In the ’80s and ’90s, Jim Kelly and Dan Marino went head-to-head 23 times (including three playoff games).

The two greatest quarterbacks of the last decade will meet for only the second time when the Packers and Colts face off Sunday. The only other time Brett Favre and Peyton Manning faced off, in Week 12 of the 2000 season, Manning threw three fourth-quarter touchdown passes, but the Packers won 26-24. Unless they meet in the Super Bowl, the two aren’t scheduled to play each other again until 2008 – if Favre hasn’t retired by then.

For years, folks have speculated that Favre’s retirement is imminent, calling upon the Packers to draft an heir apparent. But there’s no indication that he’s slowing down. Favre, who ranks second only to Dan Marino with 348 career TD passes and has the highest completion percentage of any QB with at least 5,500 pass attempts, has finished first or second in the NFL in TD passes in each of the last three seasons.

True, he’s throwing a few more interceptions and slightly fewer TDs than he did during his three straight MVP seasons. But that’s more a function of a weak receiving corps than anything else. Favre also doesn’t run with the ball as he used to, but he’s getting better at eluding the pass rush and avoiding sacks.

Since Manning has only been in the league six years, his career totals haven’t reached Favre’s heights yet, but there’s every reason to think that he’s on the same path. Like Favre, Manning hasn’t missed a game since he became a starter. That’s an important trait for a QB, especially one who hopes to finish among the all-time statistical leaders at his position. Manning has passed for more yards than any other QB in his first six seasons and ranks second in that group with 167 TD passes.

Are Manning and Favre the best two quarterbacks playing today? What tools do we have to help us answer such a question? Using cumulative statistics simply rewards longevity: Drew Bledsoe has three times as many TD passes as Tom Brady, and Vinny Testaverde has thrown for six times as many yards as Chad Pennington. That doesn’t mean that the Jets or Patriots would swap their new quarterback for their old one.

The NFL’s passer rating can also be deceptive. It blurs the distinctions between QBs like Brad Johnson, who throw the ball a lot, and ones like Jay Fielder, who play in a run-first offense. It can also distort comparisons between different eras because of the changing styles of play.

The best method, in my opinion, is one first proposed in the groundbreaking 1988 book, “The Hidden Game of Football” by Bob Carroll, Pete Palmer, and John Thorn. The authors proposed a system called Adjusted Yards, which in its basic form gave quarterbacks credit for every yard their passes gained, with a 10-yard bonus for every touchdown pass and a 35-yard penalty for every interception.

Among players with at least 75 NFL games, the QBs with the most adjusted yards per 16 games are: 1) Peyton Manning (3,784), 2) Dan Marino (3,751), and 3) Brett Favre (3,465). Furthermore, Manning and Favre are the only two active QBs with that many starts to average more than 20 TD passes per 16 games started (Favre 28.7; Manning 27.8).

Adjusted Yards can give us a good idea of the best quarterbacks in the NFL today. Taking a three-year weighted average, Manning ranks first, followed by Kansas City’s Trent Green, Aaron Brooks of the Saints, Favre, and New England’s Brady.

The popular perception of Brady is that he has tremendous intangibles and an uncanny knack for leading his team to victory. Those things are true, but he doesn’t win games by magic. He’s a tremendous passer who, like Favre, has never been blessed with a tremendous starting cast.

Green has done a remarkable job for the Chiefs, but a porous defense has made the effort mostly for naught. A similar problem has plagued Brooks, who has been mostly overlooked because he’s playing for a .500 team.

Favre and Manning may be the best passers of their generation, and they are both still in their prime. This weekend’s game offers a rare opportunity to see the two greats go head-to-head.

The RCA Dome in Indianapolis is a tough place for visiting teams to play, and Favre has always had trouble playing indoors. He’s lost 10 of the last 14 games he’s played in domes, and that doesn’t include a six-interception debacle in a 2001 playoff loss at St. Louis.

On the other hand, the Colts’ pass defense has not played well this year, and nobody’s better than Favre at finding and exploiting the weak spots in a secondary.

Manning will be hampered if Edgerrin James’s hamstring injury keeps him out of action. The Colts’ running back, who has averaged 133 rushing yards per game this year, helps take the pressure off the QB, and forces defenders to commit to containing the run. With James sidelined, Manning will face more blitzes and his receivers will face tougher coverage.