First, there was Andrew Sendejo’s misadventure on Washington’s initial touchdown. That was followed by the defensive line’s inability to get to Washington quarterback Case Keenum on the Redskins’ second touchdown. The 60,000-plus fans who were in a froth at the 1 o’clock kickoff were booing an hour later. The Eagles were in a 17-0 hole and seemed to be sleepwalking.

“We deserved all them boos,” safety Malcolm Jenkins said. “That’s the fun part about playing here. When you deserve a boo, you will get it.”

DeSean Jackson’s fireworks provided the highlights, but the defense also had a huge hand in Sunday’s come-from-behind 32-27 victory.

The Eagles defenders hadn’t played together much in the preseason — in Fletcher Cox’s case, not at all in the preseason — and spent the first 20 minutes of Sunday’s game rubbing the crust out of their eyes as Washington scored on its first three possessions.

“We were too geeked up,” said Malik Jackson, whose first game as an Eagle ended with him being carted off with an apparent left foot injury.

Cox, Jackson’s fellow defensive tackle, concurred.

“I think guys were overly excited. But then guys realized we get paid to do this,” Cox said. “Let’s just calm down and play our style of football.”

By our count, the defensive line didn’t get any real pressure on Washington quarterback Case Keenum’s first 13 pass attempts, two of which ended in touchdowns.

The first went to grieving tight end Vernon Davis when Sendejo stumbled on the coverage and then failed to make the tackle.

“Just gotta play better,” Sendejo said. “I’d have to look at the tape and see exactly what happened on that. Just gotta tighten up on some things. We can always improve and correct things for next week. Hats off to him for making that play.”

The second score was a 69-yard bomb to good-looking Redskins rookie receiver Terry McLaurin, who got behind Rasul Douglas. In fairness to Douglas, Keenum had all day to throw.

That’s when the boos came. It’s also when the defense decided to show up.

The Eagles forced Washington into three-and-outs on four of the next five possessions.

After the McLaurin touchdown, the Redskins managed only a field goal before halftime — thanks partly to a curious decision by Doug Pederson to call a timeout while Washington had the ball — and a garbage-time touchdown, which wrecked the Eagles’ chances of covering the 10-point spread.

In the second half, and prior to that final drive, Washington had 5 net yards on just three possessions. McLaurin had 104 receiving yards in the first half, 21 in the second.

Jenkins said it was just a matter of the defense getting back to fundamentals.

Cox, playing for the first time since injuring his foot in the divisional round against the Saints in January, had two tackles and two quarterback hits.

“I just had to trust myself and go out there and have fun,” he said. “I was in better shape than a lot of people expected me to be. I think I played over 30 snaps and feel pretty good about it.”