KANSAS CITY, Mo. -- While the football world might have been stunned by the Detroit Lions' 21-20 win over the reigning Super Bowl champion Kansas City Chiefs, there was one person who wasn't: Dan Campbell.

The third-year Lions head coach prepared his squad for Thursday's upset at Arrowhead Stadium, as Detroit opened the regular season 1-0 for the first time since 2017.

"I didn't learn anything, I got verification on what I already knew, and this is a resilient team," Campbell said. "It already was a resilient team and we added pieces to that resilient team, so we're built to handle some stuff and we did that today against a very good opponent."

With the Lions trailing 17-14 entering the fourth quarter, that resiliency was on display as they won their fourth consecutive road game that has been decided by one score, dating back to last season. Running back David Montgomery put the team ahead for good with an 8-yard rushing touchdown up the middle with 7:11 remaining to spoil the Chiefs' championship celebration, with fans exiting early on the night Kansas City's Super Bowl LVII championship banner was revealed.

"We expected to win this game. We came in here and we knew what we needed to do, and we knew it wasn't going to be easy and we did that," Campbell said. "Really what it means is that's one [win]. That's one. So, we've got to clean up our issues. It hurt us on some stuff today and be ready for Seattle in 10 days. That's what it is."

Slow starts have doomed the Lions over the past two years, as they posted an NFL-worst 2-14 record in Weeks 1-9 in 2021 and 2022 combined. But that wasn't the case this time around.

Dating back to early offseason workouts, even before padded practices, Lions defensive back C.J. Gardner-Johnson proclaimed that "this s--- different," in Detroit with the current players.

Gardner-Johnson signed with the Lions as an unrestricted free agent this offseason on the heels of a Super Bowl LVII appearance with the Philadelphia Eagles.

When the Lions' defense stood its ground on a crucial third-and-1 play with 5:51 left in the fourth, as defensive lineman Josh Paschal pulled down Chiefs receiver Rashee Rice on a running trick play, Gardner-Johnson was further convinced this team is legit.

"This win means that this ain't the same Detroit. I keep reiterating that. From the joint practices to all the other practices, winners know what winners look like," Gardner-Johnson said. "This team is full of winners. Being on teams that's been successful, I'm just happy to be a part of guys that want to play ball and go out here and get a W. No matter who out there on the field or what's on the clock, these guys are going to fight. S---, we're all going to fight."

With the victory, the Lions also snapped the longest active drought since defeating a defending Super Bowl champion (1997). Detroit has now won five of its past six road games but isn't satisfied as it enters Week 2's home game against the Seattle Seahawks on Sept. 17.

"It feels great. My rookie year, I feel like those games were losses for us every time, just chalk it up, but now I feel like we're going to win every game," said Lions receiver Amon-Ra St. Brown, who finished with six catches for 71 yards and a touchdown. "I go into every game thinking we better win, and if we don't, there's something wrong. That's just the mentality I feel like we all have, and I feel like that's what helps us going into games, that confidence, that swagger that we have.

"I love this team, they're a bunch of guys that I love to go to war with."