It was Feb. 4, 2007. Peyton Manning had just won the Super Bowl. He walked into the Colts' locker room, hugged coach Tony Dungy and headed for his locker.

Jeff Saturday, his longtime center, stood nearby, trying to explain the obsessive preparation that had fueled Manning's success. "We'll have a break at practice," Saturday said that night. "Everybody else will be taking it easy. Peyton will grab a bucket of water, dunk footballs in it, and make me snap them to him. At first I thought it was crazy. Now we just call it the 'Wet Ball Drill.' "

Archie Manning, Peyton's father, was standing outside the locker room when someone told him what Saturday said. "Wet Ball Drill?" Archie said. "That's a new one for me. But it doesn't surprise me."

That night it rained in Miami Gardens. Manning and Saturday were prepared. That night he won his only Super Bowl and his only Super Bowl MVP award, the greatest achievements in the career of the most prolific passer in history.

As the Vikings prepare to face Manning on Sunday in Denver, his regular-season exploits are unmatched. He may be the greatest football player in the history of NFL regular seasons, with perhaps only Jerry Rice offering competition.

There is no question that Manning is the greatest regular-season quarterback of all time. There is also no question that he cannot be called anything more.

He is not currently the best quarterback in the league. Nor is he the greatest quarterback in history. Manning's relative decline keeps him from being able to claim the former. His postseason failures keep him from being able to claim the latter.

The greatest quarterback in the game today is Aaron Rodgers.

The greatest quarterback in history is Tom Brady.

There is little more that Manning can do in a regular-season game to burnish his reputation, and there is little hope he has enough life left in his body or time left in his career to emulate Brady's body of work.

Manning's postseason record is 11-13. He has nine first-round playoff losses. He has played with a series of Pro Bowl-caliber players at the skill positions, from Marvin Harrison to Reggie Wayne to Demaryius Thomas and Emmanuel Sanders. His postseason numbers seem to be those of another, less-accomplished human.

Brady's postseason record is unmatched in NFL history. He is 21-8, for a .724 winning percentage, the highest ever. He has won four Super Bowls and three Super Bowl MVP awards. He has played well enough to win two other Super Bowls, only to have miraculous plays from the New York Giants, and dropped passes by his favorite receiver, keep him from breaking the record for most Super Bowl victories he shares with Terry Bradshaw and Joe Montana.

Unlike Manning, Brady has not played with many Pro Bowl-caliber skill-position players. When he had Randy Moss, in 2007, he produced an undefeated regular season and the most prolific season in quarterback history, which was eclipsed by Manning in 2013.

A new book by New York Daily News football writer Gary Myers, "Brady vs. Manning: The Untold Story of the Rivalry That Transformed the NFL," delves deep into the careers of Brady and Manning, and their relationship. Myers reveals that they are friends. They have spent time together at Brady's house in California with their wives. When each suffered his most serious injury, the other was sympathetic, offering moral support and advice.

Myers also writes that when Brady's undefeated Patriots faced the Giants in the last game of the 2007 regular season, Manning asked his brother Eli, the Giants' quarterback, to tell the Giants' defensive players that he would appreciate them keeping Brady from breaking his records.

Theirs is the rivalry that has defined and elevated the NFL over the past 15 years. As the Vikings face Manning on Sunday, there is little left that either can prove.

Manning is the greatest regular-season quarterback in NFL history. Brady is the greatest player in NFL history. Nothing Manning does Sunday or for the remainder of his career can change either fact.

Jim Souhan's podcast can be heard at MalePatternPodcasts.com. On Twitter: @SouhanStrib. jsouhan@startribune.com.