The New England Patriots are one game away from immortality. Yesterday, they conquered the American Football Conference, and now they need to win the Super Bowl to stake their claim as the greatest team in the history of the sport.

The Patriots’ 21–12 win over the San Diego Chargers yesterday improved their record to 18-0, giving them one victory more than the Miami Dolphins had in their unbeaten — but less dominant — 1972 season, a season that, for now anyway, stands as the only undefeated, untied year in NFL history.

As impressive as it was, the Patriots’ 18th win was more workmanlike than emphatic. The Patriots looked sluggish, they led by just two points early in the fourth quarter, and their biggest star, Tom Brady, had a particularly unimpressive game. Coming off a stellar playoff opener that followed a record-setting regular season, Brady completed 22 of 33 passes for 209 yards, with two touchdowns and a season-high three interceptions. He didn’t have a single completion more than 15 yards downfield.

New England’s next-biggest star, wide receiver Randy Moss, also had an unimpressive outing. For the second consecutive playoff game, Moss caught just one pass, and the Chargers’ cornerbacks, Antonio Cromartie and Quentin Jammer, had an excellent game. But what makes the Patriots a team for the ages is that for all the attention Brady and Moss get, New England is far from a two-man team. The Patriots won yesterday’s game on the strength of their defense, which kept the Chargers out of the end zone, and the offensive line opened huge holes for running back Laurence Maroney, who finished the game with 25 carries for 122 yards.

In fact, although the Patriots got to 17–0 thanks mostly to their passing game, they got to 18–0 in spite of it. The Patriots’ most effective offensive drive came in the third quarter, when they took the ball out of Brady’s hands and instead featured six handoffs to Maroney, mostly out of run-heavy offensive formations with three tight ends. But that 65-yard drive ended when Brady threw a terrible pass right into the hands of Cromartie in the end zone.

The Patriots’ ability to beat a good team like the Chargers despite sub-par games from Brady and Moss shows why they’re prohibitive favorites to win the Super Bowl. It also shows, however, why winning the Super Bowl isn’t a foregone conclusion — the Patriots haven’t been beaten, but that doesn’t mean they’re unbeatable. Although Gillette Stadium in Foxborough, Massachusetts, wasn’t quite as cold as Lambeau Field in Green Bay yesterday, the combination of sub-freezing temperatures and windy conditions made things unpleasant for players — and for the New England fans, who seemed oddly subdued as they watched their team march toward history. For most of the game the wind-chill factor was in the single digits, which may explain why both teams at times looked sluggish.

Injuries could also explain why San Diego looked sluggish. The Chargers claimed last week that running back LaDainian Tomlinson’s knee injury was minor, but Tomlinson was limited to just two carries — the first two plays of the game — and spent the rest of the day on the bench. Tomlinson’s injury was clearly more serious than the Chargers let on, and the league could fine the team for failure to properly disclose his injury on the official injury report.

The official injury report listed Chargers quarterback Philip Rivers as doubtful with a knee injury, but Rivers started and finished the game despite looking somewhat slowed by his knee brace. Rivers has never had a textbook throwing motion, and at times his legs looked more awkward than usual when he passed, but for the most part, Rivers was fine.

He was fine, that is, when he didn’t have Chargers linebacker Junior Seau in his face. The Patriots’ victory means that Seau, an 18-year veteran and certain future Hall of Famer, will have a chance to win his first Super Bowl ring. Playing against the team with which he spent his first 13 NFL seasons, Seau made a huge impact yesterday. He sacked Rivers once, hit him as he was passing another time, and made a great tackle to end the Chargers’ first drive of the second half, stopping running back Michael Turner on third-and-1 deep in Patriots territory and forcing the Chargers to settle for a field goal on a possession that seemed headed toward a touchdown.

Seau’s quest for a Super Bowl ring will be discussed endlessly for the next two weeks, but even more attention will be paid to the chance for Patriots quarterback Tom Brady and coach Bill Belichick to earn their fourth Super Bowl rings. Both men are, like Seau, already headed for the Pro Football Hall of Fame. But they may be headed for an achievement that eclipses even that honor. At Super Bowl XLII, the Patriots can achieve perfection.