PHILADELPHIA -- Most of the pre-game hype was about the quarterbacks - one who used to play for the Philadelphia Eagles and one who still does.

In the end, however, it was the defense that carried the Eagles to a 21-10 upset of the Minnesota Vikings on Sunday at Lincoln Financial Field. The decision was the first defeat for the NFL's final undefeated team.

"We take a lot of pride on our side of the ball and we got our butts handed to us last week (by the Washington Redskins)," Eagles defensive end Connor Barwin said. "We wanted to show everybody - and especially ourselves - that the team they saw last week wasn't the real Philadelphia Eagles. This one was."

Neither team's offense was very effective and neither team's quarterback played especially well. Philadelphia rookie Carson Wentz completed 16 of 28 passes and had a passer rating of 52.4.

Sam Bradford, who was traded to Minnesota the week before the season opener, was even worse for most of the game. He completed 24 of 41 passes and had a passer rating of 71.5, but most of that came late in the fourth quarter when the Eagles were conceding short passes. Before the Vikings' final possession, Bradford was 15 of 32 with a passer rating of 45.7.

"Embarrassing, really, is the word for it," Vikings coach Mike Zimmer said of the defeat. "I was very disappointed in the performance we gave today. We made too many mistakes and if you're going to do those things you have no chance to win."

"Those things" included: Five fumbles, three of which were recovered by the Eagles; an interception in the end zone (Bradford's first of the season); six sacks (the Vikings gave up eight sacks in their first five games), not to mention several dropped balls and errant passes by Bradford.

Plus the Eagles, who gave up 230 rushing yards to the Redskins last week, held the Vikings to just 93 yon the ground and 29 of them came on one carry. And the Vikings had the ball inside the 20 three times and came away with zero red-zone points, including a first-and-goal from the 1.

"The way we played today was unacceptable," Bradford said. "Obviously, we did a lot of (negative) things that we didn't do in the first five weeks, things that keep you from winning football games."

And just as obviously, forcing those mistakes help you win football game. That's why the Eagles coach and best their defensive player used the same word to describe Sunday's game - "fun."

"It was fun watching our defense today," Eagles coach Doug Pederson said.

Said defensive lineman Fletcher Cox: "No. 1 thing we saw today was we got back to where everyone was having fun."

The first quarter wasn't much fun for football purists, as the two teams turned the ball over on five consecutive possessions covering just 11 plays. The Vikings (5-1) received great field position when Wentz threw his second interception of the year, taking over on the Eagles' 11. But two plays later, Bradford threw his first interception of the season, which was picked off by safety Rodney McLeod in the end zone.

Then, on the Eagles' next possession, Wentz and running back Darren Sproles missed connections on a handoff and the Vikings recovered on the Eagles 17. But then Barwin knocked the ball out of Bradford's hand and safety Malcolm Jenkins returned the ball 76 yards for an apparent touchdown - until the officials ruled that he had been touched when he was on the ground.

The Vikings finally broke the ice when Blair Walsh kicked a 48-yard field goal with 9:01 left in the second quarter for a 3-0 lead.

The Eagles (4-2) needed exactly 13 seconds to erase that lead, as Josh Huff returned the ensuing kickoff 98 yards for a touchdown. After the point-after was made, the Vikings were flagged for roughing the kicker and the Eagles decided to take the penalty and go for the two-point conversion from the 1. And they got it when Wentz ran a quarterback draw and banged into the end zone for an 8-3 lead.

The Eagles added a field goal right before halftime and then their defense took over after that. Bradford was sacked twice on Minnesota's first possession of the second half and the Vikings were forced to punt. Wentz then led the Eagles on a 77-yard scoring drive, throwing a 5-yard TD pass to wide receiver Dorial Green-Beckham for an 18-3 lead with 5:45 left in the third period

NOTES: Vikings WR Stefon Diggs was back in the lineup after missing the last game with a groin injury. But rookie WR Laquon Treadwell, the first-round pick from Mississippi, was deactivated with a thumb injury. Treadwell, who has now missed three of the Vikings' six games, is still looking for his first NFL reception. ... The Eagles played without starting DT Bennie Logan (groin). Beau Allen started in his place. ... Josh Huff became the fifth Eagles player to return more than one kickoff for a TD. The others: Timmy Brown (five times), Derrick Witherspoon (three), Steve Van Buren (three) and Brian Mitchell (two).