FOXBORO - For once, Bill Belichick said his team could look ahead.

But after 18 one-game winning streaks, with just one mountain left to climb in two weeks' time at University of Phoenix Stadium in Glendale, Ariz., the head coach of the New England Patriots did not say it was time to start looking back.

"It's been one week at a time for us, it really has," Belichick said. "I think there will be a time and a place to sit back and reflect on it. Right now, I'm just proud of our team for winning this game and having a chance to go play for the NFL title."

With Sunday's 21-12 victory over the San Diego Chargers at Gillette Stadium, the Patriots have earned their fourth trip to a Super Bowl in Belichick's eight-year tenure as head coach. They'll be playing the team with which Belichick made his mark as a defensive genius, the New York Giants, who defeated the Green Bay Packers 23-20 in overtime later Sunday.

It wasn't an easy victory for the 18-0 Patriots, even with Chargers' quarterback Philip Rivers hobbling around heroically and all-everything running back LaDainian Tomlinson looking decidedly less heroic on the Chargers' bench with a sore knee after just two carries. But as Belichick said, his players "did everything they needed to do to beat an outstanding football team." In the process, they survived three interceptions by Tom Brady - his worst playoff performance since being picked three times last year against the Chargers in the divisional round - and three forays of the depleted Chargers into the red zone that produced only nine San Diego points.

"It's a real privilege to coach this group of guys, and they stepped up and made the plays again today like they have all year," said Belichick - who, for the first time this year, didn't tell the assembled media that his team had a long way to go to reach its goal. The goal is now within reach.

For 18-year veteran linebacker Junior Seau, who went to a Super Bowl and lost in the 1994 season, Sunday's victory over his hometown team represented "a chance" for redemption.

"You know, coming here to New England with the Kraft family and the Belichick family, all anyone wants - I don't care if you're a rookie to an 18-year vet, I don't care if you're a third grader - all we ever want in life is a chance, just a chance," he said. "Does that mean a chance to win the Super Bowl? No, a chance to win. And when you win often, it leads into greater things. And you learn that during the course of life. It's just, give an old man a chance."

The chance comes thanks to a red-zone defense that played stout when it needed to, the members of a much-maligned backfield that produced with others couldn't, and because the focus and direction of this team is impossible to distract, no matter how some might try.

"It's nice to know you can win the close ones," said Brady (22-33, 209 yards, two touchdowns). "It's nice to know you can win the ones when you face some adversity and you've got to be mentally tough. It's nice to have the blowouts, too.

"Any way you get the win is great," he said. "I think you come into a game like this, you want to play your best and I don't think we necessarily played our best, but at the same time, you have a chance to redeem yourself and play in the biggest game of the year."

Brady's interceptions (by Quentin Jammer, Drayton Florence and Antonio Cromartie) were most disconcerting. He didn't lose the divisional-round game last year despite having thrown three, but rarely does anything good come from turnovers - as Brady was reminded on the Patriots' third possession of the game, when he was picked off by Jammer on a sideline throw intended for Donté Stallworth at the New England 40.

On the first play of the San Diego possession, Vince Wilfork was called for a personal-foul face-mask penalty on a 5-yard run by Michael Turner, putting the Chargers at the Patriots' 20. Then, a sideline pass from Rivers to Chris Chambers gave San Diego a first down at the 9.

But the drive stalled there, and after Chambers came down with the ball out of the end zone on a third-down pass, the Chargers had to settle for Nate Kaeding's 26-yard field goal and a 3-0 lead with 2:55 left in the first quarter. The San Diego score seemed to awaken something in the Patriots. Taking over at their own 35, they started moving positively on a 9-yard pass to Wes Welker and a 14-yard reverse run by Randy Moss, followed by a 14-yard Brady-to-Kevin Faulk throw on the left sideline to get to the Chargers' 25.

Laurence Maroney (25 carries, 122 yards) later picked up 7 yards for a first down on a third-and-1 sweep to the San Diego 9, and a throw to Faulk (eight catches, 82 yards) to the 1 set up Maroney's blast off right guard for the go-ahead score with 13:48 left in the half.

Despite his immobility, and with Tomlinson on the bench with am aggravation of his hyperextended knee, Rivers still found ways to get the ball to open receivers on the ensuing possession. He fired for 15, 16 and 21 yards to Vincent Jackson, the latter for first and goal at the Patriots' 9, but again, the New England defense stiffened inside the 10, and when Ellis Hobbs tripped up Chambers for just a 3-yard gain to the 5 on third down, again the Chargers had to settle for Kaeding's 23-yard field goal.

Special teams played a role in setting up the next Patriot score when Kelley Washington went high in the air to prevent a Chris Hanson punt from going into the end zone, and Kyle Eckel downed it at the San Diego 4.

On the fifth play of the possession, Rivers was in the process of being tripped up by Mike Vrabel when he tried to throw over the middle to Chambers, only to have Asante Samuel step in front of him and intercept the ball.

"It was probably our turn to win a game," Vrabel said. "Yeah, I think that was the Patriots of olde, where you would just kind of hang around and make the big plays and make the plays when it counted and defense would play well in the red zone, force them to kick field goals."

Given a gift scoring opportunity at the San Diego 24, Brady didn't disappoint. After a 12-yard throw to Faulk on the right sideline, Brady found Jabar Gaffney on a left-to-right crossing pattern, and he made an untouched sprint to the end zone to complete the 12-yard scoring play with 3:51 left in the half, putting the Patriots up 14-6.

An interception by Hobbs (and fumble recovery by James Sanders) ended another San Diego foray into Patriot territory, but the Patriots had to kick the ball back to the Chargers, and a 36-yard ramble by Darren Sproles set up another scoring opportunity, cashed in when Kaeding hit a 40-yarder with eight seconds left.

Kaeding hit another 24-yarder with 8:36 left in the third quarter, ending a drive made possible when a Brady throw off Stallworth's hands was intercepted by Florence at the Patriots' 49.

Rivers threw for 17 yards to Jackson and 19 yards to Chambers to get to the 13, and for 6 more to Jackson. But on the second try by Turner, Seau broke through the line to drop the reserve running back for a loss of 2 yards, and force the field goal that kept the Patriots in a slim 14-12 lead.

Brady was intercepted for the third time with 2:56 left in the third quarter, this time by Cromartie as Brady tried to get the ball to Benjamin Watson in the back of the end zone on third-and-goal from the 2. The Patriots had marched from their own 33 in eight plays before the turnover, with Maroney carrying five times for 39 yards in the abortive march.

Maroney was the man when the Patriots got the ball after a three-and-out. After a 13-yard pass to Heath Evans started the march, the second-year running back carried four times for 29 yards and took a screen pass 9 yards behind Logan Mankins' block, setting up Brady's 6-yard crossing-pattern TD pass to Welker with 12:15 left to play.

Getting the ball back with 9:13 left, the Patriots went into lockdown mode. Two big third-down catches by Faulk moved the stakes, and Maroney was able to close out the Chargers by carrying six straight times before Brady could go to his knee twice and end the game.

Belichick was practically giddy as he passed credit up and down his 53-man roster.

"I'm happy for all our players, I really am," he said. "I'm happy for the guys who have been there before and the new guys that have come in this year, Junior and Randy and Wes, all those guys. We have a lot of guys we brought in there and even some of the younger kids that have just been here the last year or two, and this is their first experience, and Laurence.

"Everybody had a big role in this team and this season, and this game today, and I'm happy for all of them," he said. "They all deserve it."

MARK FARINELLA may be reached at 508-236-0315 or via e-mail at mfarinel@thesunchronicle.com