Patriots QB Tom Brady directs his offense against San Diego in September, when the teams first met this season.

The Providence Journal/ / Bob Breidenbach

FOXBORO — Tom Brady knows now that he was naivÉ.

In the hours before the first-year starter and his New England Patriots teammates were to play in Super Bowl XXXVI, Brady took a nap in the locker room at the Superdome. He and the Patriots made history that day, scoring one of the biggest upsets in NFL history and winning the franchise’s first championship.

Things have changed for the quarterback since then. When New England steps on the field this afternoon to face San Digeo, it will be the team’s fifth AFC Championship Game appearance in the last seven years, and Brady, as well as many of the team’s veteran players, know how to handle the pressure.

“I was naïve back in the day,” Brady said Friday. “My first couple years, I thought it was easy…. ‘hey, this is no problem. You start a few games, you’re in the Super Bowl and U2 is out there playing on the field.’

“Now you kind of know what to avoid, so you lose a little bit of that naivetÉ and you just focus on whatever you need to focus on.”

The experience of being here before could make a difference for the Patriots; the majority of the players played for the AFC title a year ago, and nearly two dozen have been with the club for at least one of its Super Bowl victories.

By contrast, the Chargers haven’t advanced to the conference championship game since 1994, and only one member of the current roster — long snapper David Binn — was with the team then.

Only three other San Diego players: tight end Brandon Manumaleuna (St. Louis 2001), fullback Lorenzo Neal (Tennessee 1999) and tackle Roman Oben (Tampa Bay 2002) have been this deep into the playoffs before.

There are some of the belief, San Diego probably included, that being so green when it comes to such a big game won’t matter for the Chargers.

But there are lessons to be learned, both positive and negative, from being part of what Tedy Bruschi calls a “hat and T-shirt” game, since that’s what the players on the winning side will receive as conference champs.

“It gives you experience. I know what it’s like to win it, I know what it’s like to lose it — you know, both sides of the spectrum,” Bruschi said.

While Bill Belichick always emphasizes a one-week-at-a-time approach and that’s been no different this week, he also puts a premium on preparation and stressing what’s at stake.

“It’s the AFC Championship Game,” Belichick said. “Our whole season and San Diego’s whole season rests on this one game. We know what’s at stake, and so does everybody else.”

After its difficult loss to Indianapolis last January, when the Pats dominated the first half and seemed to wear down in the second, avoiding such a collapse again is a motivating factor for most, in addition to being able to continue their pursuit of another Super Bowl title, which would give them the NFL’s first 19-0 season.

“Hopefully we learned some valuable lessons from that game last year,” Brady said. “I’ve seen a lot and as a team, I think we’ve been through a lot. So hopefully we can draw back on those experiences and hopefully use them.”

Over the last 364 days, the Patriots have changed and endured: Randy Moss, Adalius Thomas and others were brought on board to help fill the team’s most glaring weaknesses; the suspension of Rodney Harrison, Spygate, and the pursuit of an undefeated season helped galvanize the players.

But as Belichick said this week, all the preparation they’ve put in have gotten them only to the same point that they got to last season.

They’ve dealt with the hype, this year and in the past. And knowing how to do that might tip the scales in their favor.

“This is the fifth AFC Championship Game that we’ve been in in the last seven years, so there are players that have been a part of a lot of those teams,” Brady said. “We’re going to try to use what we’ve learned in the past to our advantage, wins or losses.”

smanza@projo.com