On a gloomy, slippery, sodden afternoon, Jalen Mills' neon-green hair shone forth from the Eagles' sideline like a beacon, lighting the way to a 33-10 victory for the NFL's only 7-1 team.

Mills' 37-yard interception return for a touchdown just before halftime was the dagger, the play that showed the visiting San Francisco 49ers that even if Carson Wentz and the offense were struggling a bit, the defense would make sure the 49ers weren't going to hang close and find a way to pull their first victory of the season out of the Lincoln Financial Field muck.

Defensive end Brandon Graham said he'd just been thinking that the defense needed to "flip the field," and: "We went out there and got the interception, that boy Jalen scored. We just took off from there."

The Eagles, up just 3-0 at the two-minute warning, got a touchdown pass from Wentz to Zach Ertz with a minute and 51 seconds left. Then, three snaps later, San Francisco rookie quarterback C.J. Beathard looked to veteran receiver Pierre Garcon on a sideline route that Mills read all the way. The second-year corner broke on the ball effortlessly, tucked it away, then began his journey to the end zone.

"Been watching film hard all week. Been kinda studying that route, too," Mills said. "Knowing Pierre Garcon, he's their possession receiver, also best route-runner. Seeing the motion go over to the single receiver side, knowing the rookie quarterback was gonna try to work him. Soon as I got the stem [route] that I'd been seeing all week on film, kinda just trusted my feet, trusted my technique and my safety over the top [to make the tackle if Mills missed] to jump the route and pick the ball off."

Mills went straight down the visiting sideline to about the 49ers' 12. Then, he said, he started thinking about some kidding he'd been taking from safety Malcolm Jenkins, defensive coordinator Jim Schwartz and defensive backs coach Cory Undlin.

"I was actually about to go out of bounds," Mills said. "Then I thought about it. Malcolm, coach Schwartz and coach Undlin, they'd been grilling me all week, talking about how I had no return skills. That kind of went through my mind, so I cut it back. I had to get into the end zone, or I wouldn't have stopped hearing that, for certain."

Mills cut toward the middle, gliding in front of the prone figure of 49ers left tackle Joe Staley, who was down with an eye injury that would end his day. Nigel Bradham, Fletcher Cox, Jaylen Watkins and Dexter McDougle threw blocks as Mills kept running horizontally, then finally found a hole to dart through, into the end zone. A two-point conversion pass made up for Jake Elliott's first of two missed extra points, and it was 17-0 at the break.

Watkins said he when he saw Beathard throw to Mills' side,  "I didn't see a receiver anywhere in sight. " He said he saw Mills make the pick, "and I thought he was going to just give up. Because once you get a pick, sometimes, you're like 'Oh!' – you're too happy [to do much with it]. Then he cut back across the field … Everybody else was like 'OK. We got our guys blocked for him.' "

"Credit his vision on that," said safety Rodney McLeod, whose earlier interception of Beathard helped show the rookie QB he was in for a long day. "I thought he was going to take it straight down the sideline. … It was a big play for us right before the half, and it created a lot of energy and momentum in the building."

San Francisco coach Kyle Shanahan said Mills "was playing off, reading the quarterback, and really wasn't looking at the receiver. The ball was just a hair inside, and he made a great play."

Eagles coach Doug Pederson correctly noted that pressure off the edge from rookie defensive end Derek Barnett helped set up the pick. The Birds' front seven dominated the game, even without middle linebacker Jordan Hicks, out for the season with an Achilles' tear suffered last week.

Barnett jumped on Mills in the end zone, delaying the celebration of Mills' third interception of the season, his first ever at the Linc.

"Jalen's playing with a lot of confidence," Pederson said. He said Mills is "a player that we lean on to do a lot of things. He's also physical in the run game."

When Robinson suffered an apparent concussion on McLeod's interception, the Eagles mixed up their coverages, with Mills sometimes taking Robinson's place in the slot, instead of playing outside.

Mills said that "based off formation, what side the ball was on, [I] just slid inside."

Beathard, sacked four times, threw for just 144 net yards, 17 of 36 for 167, with a long gain of 24. The 49ers managed just four passing first downs.

Mills' photo and his nickname – "The Green Goblin" – graced the cover of the Eagles' game program.

"I gotta give those to my mom and my granny," Mills said, resting his elbow on two boxes of programs delivered to his locker stall.

Two boxes?

"I got a big family," he said, as he trundled toward the parking lot with the magazines balanced on the handle of his rolling suitcase.