The Seahawks will not win the NFC West for a fifth straight season, and the Arizona Cardinals will capture their first division title since 1975 - when they were still the St. Louis Cardinals.

It's not official, not just yet anyway. But with their 26-20 victory over the still-stumbling Seahawks on Sunday, the Cardinals are 7-3 and have a five-game lead over Seattle with six to play.

"They won the division," linebacker Julian Peterson said after the Seahawks fell to 2-8 and lost at home for the fourth time in five games.

"That's plain and simple. They beat all of us (including the division-rival 49ers and Rams). It's something we have to deal with."

This is not how this season was supposed to unfold. Even at 2-7, and as ludicrous as it sounds, the players were clinging to the hope that they could get on a roll, sweep the Cardinals and still be a factor in the division - especially with quarterback Matt Hasselbeck and flanker Deion Branch returning to the lineup after missing the past five games because of injuries.

Not anymore. Not after losing to the Cardinals at home for the first time since 2002.

"This was a huge win," Cardinals quarterback Kurt Warner said. "Not only because we came out and played well, but the significance of this win for us at this point of the season.

"A lot of things were riding on this game, so it was huge."

And Warner came up huge in a stadium where he had thrown six interceptions and been sacked 10 times in his past two appearances.

On Sunday, Warner put together his fourth straight 300-yard passing performance by completing 32 of 44 passes. Thirteen of his completions, and 337 of his 395 passing yards, went to Anquan Boldin (13 for 186) and Larry Fitzgerald (10 for 151).

By comparison, an admittedly rusty Hasselbeck threw three interceptions on a day when his passer rating was 47.3 - or less than half that of Warner (98.2).

For the Cardinals, the first half of the game resembled a 7-on-7 passing drill, the kind every team uses in practice where there are no defensive linemen to rush the passer.

Warner took advantage of the Seahawks' inability to pressure him, and the zone coverage in the secondary, to slice, dice and dissect the defense in staking the Cardinals to a 16-7 halftime lead. They extended the lead to 19-7 after scoring on their first possession of the second half.

Warner was 18 of 20 for 213 yards on the Cardinals' first three possessions - drives of 60, 89 and 65 yards.

"We let him get too comfortable," free safety Brian Russell said. "If he's comfortable back there, with those weapons outside, let's just say that's not what you want."

But despite falling into the kind of hole they haven't been able to dig themselves out of this season, the Seahawks did battle back.

They scored twice in the fourth quarter on two short runs by T.J. Duckett to cut the Cardinals' lead to six points.

A defense that had been pushed around in the first half found a way to push back in the fourth quarter.

"We finally started doing a good job of getting a hand in his face," Peterson said. "(Warner) started getting a little frantic back there."

After linebacker Karlos Dansby intercepted a Hasselbeck pass in the end zone, tight end John Carlson forced a fumble that was recovered at the Arizona 11-yard line by left tackle Walter Jones.

Five plays later, Duckett scored on a 1-yard run, after also getting the needed yard on a fourth-and-1 play.

On the Cardinals' next possession, defensive tackle Brandon Mebane hit Warner as he was about to throw and defensive end Darryl Tapp recovered the loose ball at the Arizona 14.

Five plays later, Duckett scored on a 2-yard run.

The defense then held twice, forcing the Cardinals to punt for the only two times in the game.

"It was a wrap. It was a game-winner," Peterson said. "Our offense normally pulls out games like that."

Not this game. Not in this season. The comeback - and the Seahawks' season - was snuffed out when Hasselbeck's pass to Branch with roughly two minutes to play instead found Cardinals cornerback Dominique Rodgers-Cromartie.

Hasselbeck was looking to, as he put it, "throw a home run post to Deion." Instead, Hasselbeck threw the ball somewhere between the flat and deep. Rodgers-Cromartie undercut the play and made the pick.

Coach Mike Holmgren calls this zigging when they should have zagged. It has happened often enough this season - in all phases of the game - to cause the team to careen out of control, and finally out of the division race.\

GAME AT A GLANCE

PLAYER OF THE GAME

Kurt Warner. The 37-year-old ((age)) former Arena League and NFL Europe quarterback had washed out with the Rams, the Giants and supposedly the Cardinals. But here he is, once again putting up MVP-type numbers in leading his team to a 7-3 record. Sunday, Warner was 32 of 44 for 395 yards - with 23 of his completions going to the dynamic duo of Anquan Boldin (13) and Larry Fitzgerald (10) for 337 yards. The Cardinals jumped on top 26-7 because Warner pounced on the Seahawks with his precision passing. He was 9 of 10 on their first scoring drive, 4-for-4 on the second and 5 of 6 on the third.

PLAYS OF THE GAME

Offense: With the Cardinals holding a 16-7 lead in the third quarter and facing second-and-15 at their own 28, Warner unleashed what was his most impressive throw in a day filled with them. Boldin had gotten behind middle linebacker Lofa Tatupu up the middle of the field when Warner found him with a 44-yard strike. The atypical completion - since most of his throws were of the shorter, higher-percentage variety - set up the last of Neil Rackers' four field goals.

Defense: The Seahawks got the ball with 2:05 to play and the Cardinals clinging to a six-point lead. But on first down, quarterback Matt Hasselbeck went to Deion Branch only to find Cardinals cornerback Dominique Rodgers-Cromartie. The interception, Hasselbeck's third, sealed the victory for the Cardinals - not to mention the fate of the Seahawks as they trudge into their final six games.

Special teams: On the final play of the first half, Rackers nailed a 54-yard field goal to give the Cardinals a 16-7 lead. It was the third of his four field goals, and just a yard shy of tying his career long - a 55-yarder against the Seahawks in 2004. This one was Rackers' seventh field goal of 50-plus yards against Seattle.

- Clare Farnsworth

P-I reporter Clare Farnsworth can be reached at 206-448-8016 or clarefarnsworth@seattlepi.com Read his Seahawks blog at blog.seattlepi.com/Football.