SEATTLE -- Matt Cassel coolly completed passes with blitzers swarming him. Wes Welker lowered his head into and out of piles for key gains. An injury-depleted defense needed recently signed veteran Junior Seau, then turned stout when it had to.
Even though it was against a struggling opponent, the New England Patriots showed championship-like resolve to begin their favorite month.
Cassel handled the blitzes for completions with his team's playoff chances in the balance. Then Sammy Morris leaped into the end zone from 1 yard on fourth down with 2:44 remaining and the Patriots rallied past the Seattle Seahawks 24-21 on Sunday to reclaim a share of the AFC East lead.
"Trust me, if we don't take care of this game there is no tomorrow," Seau said.
The 39-year-old was home surfing last week. Then two days after he returned from retirement, he was forced into action when Tedy Bruschi injured his knee in the second quarter.
The Patriots (8-5) withstood injuries to three other defensive starters, a rare two-touchdown receiving day by former teammate Deion Branch and a 21-13 deficit early in the fourth quarter to improve to 21-2 in December since 2003.
They forged a three-way tie for first place in their division with the New York Jets and Miami after Brandon Meriweather sacked Seneca Wallace near midfield with 1:54 left. Richard Seymour recovered the fumble to clinch it.
"Hey, looking good, huh?" Meriweather said.
Meriweather, the first-round pick New England received from Seattle for Branch in 2006, ran past the failed block of fullback Leonard Weaver on an overloaded blitz.
Wallace had twice called time out before plays to avoid facing that blitz. But he had none this time, because Seattle had spent its final one earlier in the fourth quarter when its defense had 12 men on the field.
How big was that play for New England's season?
"I think you know," Meriweather said, smiling and shaking his head. "It was a relief."
One week after flopping with four turnovers in a home loss to Pittsburgh that put New England on the outside rail of the AFC playoff race, Cassel was 26 of 44 for 268 yards passing and a touchdown, with no turnovers.
New England improved to 18-1 after losses since 2003.
"A huge win," Cassel said. "We knew the season was on the line."
Wallace, making the ninth start of his six-year career because Matt Hasselbeck's back is hurting again, was 20-for-28 with 212 yards passing and a career-high-tying three touchdowns. Yet Seattle (2-11) lost for the sixth consecutive time and has its worst record since a franchise-worst 2-14 season in 1992.
Outgoing coach Mike Holmgren had to catch himself from breaking down afterward while discussing how proud his was of his team. It controlled most of the game with an up-tempo offense that had New England reeling -- until Cassel and Meriweather trumped it.
"This game showed that the players are giving me everything they've got," Holmgren said three weeks before he ends his 10-year tenure as Seattle's coach.
Cassel looked more like the guy who had consecutive 400-yard passing games than the one the Steelers harried into four turnovers in New England's 33-10 loss at home last week.
After New England decided to counter Seattle blitzing with one-step drops and quick passes that were essentially extended handoffs, Cassel was 5-for-8 on the decisive drive that began with 8:47 left at the New England 29. He converted third-down throws to Jabar Gaffney and Welker, who caught a season-high 12 passes for 134 yards.
Welker's third catch of the drive included a stiff-arm of safety Brian Russell on a 25-yard play to the Seahawks 6. Three runs later, Morris jumped in off left guard for the score.
"They blitzed us and they were coming after him and he did a great job of keeping some poise," Welker said of Cassel.
Branch had given Seattle its 21-13 lead late in the third after a 63-yard catch and run on which he faked Seau. Then he tipped a 4-yard touchdown pass to himself with his left hand.
After his 14-yard scoring catch began the scoring, the former Super Bowl MVP with the Patriots took a bow and kept the ball after his first touchdown since Dec. 16, 2007. He has been injured for much of his time in Seattle.
"I'd rather take one catch and win the game," Branch said. "It's sad, man ... You'd almost rather lose by three touchdowns than to lose that way."
- New England was already missing OLB Pierre Woods, who was inactive for the first time this season with a jaw injury. DT Vince Wilfork went to the locker room in the first quarter with a shoulder injury. S James Sanders left in the third quarter after hurting his ribs.