FOXBOROUGH, Mass.

LaMichael James awaited the kickoff, determined to regain the momentum for the 49ers after they quickly lost all of a 28-point lead.

“We need a boost,” he said. “That’s what I was thinking. I was thinking I got to take it to the house.”

He didn’t get all the way there, but close enough to set up the decisive touchdown — going 62 yards before Colin Kaepernick’s 38-yard pass to Michael Crabtree with 6:25 left — that helped San Francisco reach the playoffs with a 41-34 win over the New England Patriots on Sunday night.

“We faced adversity,” James said. “Nobody flinched.”

Now the 49ers have at least a wild-card berth with a 10-3-1 record, knowing a win against division rival Seattle (9-5) next Sunday clinches the AFC West title.

The Patriots (10-4) already had locked up first place in the AFC East with a chance to improve their chances for a first-round bye.

They began the day in second place in the race for the two byes but fell behind the Denver Broncos (11-3). The Houston Texans (12-2) hold the top spot.

“We haven’t thought about that yet,” Tom Brady said. “What’s in our control is winning football games.”

Doing that on Sunday night seemed almost impossible after the 49ers rolled to a 31-3 lead on Kaepernick’s 27-yard touchdown pass to Crabtree five minutes into the third quarter. Only one team in NFL history had won a regular season game after trailing by 28 — a 38-35 win by the 49ers over the New Orleans Saints on Dec. 7, 1980.

But with 25 minutes left and Brady at quarterback, the 49ers weren’t comfortable.

“Tom is a good quarterback and we knew some adversity was going to come and they were going to make plays sooner or later,” linebacker NaVorro Bowman said.

They did — time after time — until they had tied the score at 31 on Danny Woodhead’s second touchdown, a 1- yard run with 6:43 remaining.

Woodhead began the comeback with a 6-yard touchdown run, Brady scored on a 1-yard sneak on the first play of the fourth quarter and then threw a 5-yard touchdown pass to Aaron Hernandez less than three minutes later.

And when Woodhead scored again, the Patriots had their fourth touchdown in 14 minutes, 16 seconds.

But two plays later — James’ kickoff return and Crabtree’s catch — the 49ers were back on top. And this time they stayed there.

David Akers made it 41-31 with a 28-yard field goal with 1:56 to go, Stephen Gostkowski kicked a 41-yarder for New England with 38 seconds remaining and San Francisco sealed the win when Delanie Walker caught the onside kick.

“We just spotted them 28 points,” Brady said.

“We fought hard, but you can’t play poorly against a good team and expect to win. We can’t miss plays that we have opportunities with.”

For Kaepernick, a secondyear pro starting just his fifth game, it was a chance to remain calm even as the big lead disappeared.

He finished with 14 completions in 25 attempts for 216 yards and a career-high four touchdowns.

“This is my 17th year of football,” he said.

“I’ve been playing since I was eight years old. So, to me, I am going to go out there and I’m going to throw to the guy who is open and you try to keep football simple so your mind can be clear when you’re on the field.”

New England, which had won seven straight games, lost for the first time at home in December in 21 games.

NOTES: The 49ers allowed 520 yards after entering the game second in the NFL in fewest yards allowed, 275.5 per game. … Welker had five catches, giving him 100 and making him the first player in NFL history with that many in five seasons. … Gore led all rushers with 83 yards on 21 carries. … Brady was 36 for a career-high 65 for 443 yards, one touchdown and two interceptions.