Tom Brady's New England Patriots stunned by Kansas City Chiefs: 'We just wanted to come out and shock the world'

Rookie running back Kareem Hunt upstaged Tom Brady as the Kansas City Chiefs launched the new National Football League season with a stunning 42-27 upset of the New England Patriots on Thursday.

Chiefs quarterback Alex Smith threw for 368 yards and four touchdowns to puncture the festive atmosphere as the Super Bowl champion Patriots raised their championship banner in the traditional season kick off at Gillette Stadium.

But it was Hunt, 22, who stole the show for the Chiefs, recovering from a fumble on his first possession to finish a debut to remember with three touchdowns.

"We just stuck together," Hunt said. "We're like the underdogs, a lot of people didn't believe in us. We just wanted to come out and shock the world."

Smith meanwhile produced a virtuoso display at quarterback for the Chiefs, completing 28 of 35 pass attempts with no interceptions.

Brady had a frustrating night, throwing for 267 yards and no touchdowns. The 40-year-old five-time Super Bowl champion completed only 16 of 36 attempts.

"It's a terrible feeling," a stony-faced Brady said after the defeat. "But the only guys that can do something about it are back in that locker room. We've got to dig a lot deeper than we did tonight. Because we didn't dig very deep tonight."

Patriots coach Bill Belichick was typically blunt in his assessment of the loss.

"We didn't really do much of anything well enough to deserve a win," Belichick said. "We gave up 42 points. Gotta coach better, gotta practice better, gotta play better.

"We've got a lot of work to do. That's obvious. So we'll go back to work and see if we can improve pretty much everything. We made too many mistakes and our fundamentals weren't good enough."

Patriots fans had launched the evening in Foxborough in raucous mood, raining boos down on NFL commissioner Roger Goodell at the opening ceremonies.

Brady was quickly into his groove, leading a nine-play, 73-yard drive that culminated with Mike Gillislee's two-yard touchdown run.

The Pats looked to have grabbed another touchdown after recovering a Chiefs fumble, only for Rob Gronkowski's end zone reception to be deemed incomplete after a video review.

Instead it was the Chiefs who recovered, getting on the board when Demetrius Harris gathered Smith's seven-yard pass after a 90-yard drive.

A Stephen Gostkowski field goal and a second Gillislee touchdown saw the Patriots go 17-7 up but Hunt's first touchdown of the night from a three-yard Smith pass pulled the Chiefs back to 17-14.

A superb 75-yard touchdown pass from Smith to Tyreek Hill then put the Chiefs 21-17 ahead only for Gillislee to barrel over from one yard to put the Patriots 24-21 ahead with 5:01 remaining in the third quarter.

A further Gostkowski field goal stretched the Patriots lead to 27-21 but Kansas City hit back almost immediately with a brilliant 78-yard touchdown from Smith to Hunt to put the Chiefs ahead.

The Chiefs stopped the Patriots on a crucial fourth and inches early in the fourth quarter, and Hunt then dived over in the corner for his third touchdown of the night to make it 35-27.

Charcandrick West then added another touchdown to complete the scoring for the Chiefs.