DANVERS — Eighteen is an eternity in coaching years.

That’s how long Central Catholic coach Chuck Adamopoulos waited before he was able to enjoy his second career win at St. John’s Prep.

His fourth-ranked Raiders ended the drought on Saturday afternoon, riding a stingy defensive performance to a 21-14 victory over No. 7 Prep.

“We haven’t won here since 1998, my second year as head coach,’’ Adamopoulos said, “We’ve had some great games here but we’ve always been on the short end, so to win a game like this is really nice.’’

With less than 90 seconds left in a 14-14 game, and Central on the Prep 18, Adamopoulos inserted his backup quarterback, 5-foot-9-inch, 175-pound senior Matt Horgan, into the game.

Operating out of a wildcat formation, Horgan faked a handoff and blazed ahead, riding a push from his offensive line into the end zone for the go-ahead score.

“I put [Matt] in as a changeup,’’ said Adamopoulos after the Raiders earned their first win over Prep since 2011.

“He’s a good little competitor. That was big.’’

Central then tried to give it back.

A botched pooch kick, and a personal foul had Prep on the Raiders’ 45 with 1:16 left.

Adamopoulos’s defensive unit, however, was not fazed.

On third and 5, Central junior linebacker Max Faro lowered his shoulder on Prep senior back Joe Masterson, jarring the ball loose with a resounding hit.

Senior cornerback Johandy Gonzalez pounced on the fumble, putting the finishing touches on a program-defining win.

“I came off the block and Max came out of nowhere,’’ Gonzalez said. “The ball popped out and I just dove on it.’’

While Gonzalez contributed to the final score, it was his counterpart in the secondary, senior Mathias Villafane, that broke the game’s biggest play while he was lined up at receiver.

On the first snap of the second half, Raiders junior quarterback Bret Edwards (16 of 19, 182 yards) found Villafane in the flat. With a lethal combination of breakneck speed and lateral quickness, Villafane sliced through the St. John’s defense for a 63-yard score.

“I love the kid,’’ Adamopoulos said of Villafane. “He loves football and he’s a hard worker. He’s an awesome kid to coach.’’

With Central up, 14-7, offensive stagnation became the story, as both defenses forced their opponents into multiple three-and-outs.

But with 4:15 remaining in the game, Prep quarterback Mike Yarin’s jump ball was snared in the end zone by Michael Galatis for a 22-yard reception that tied the game, 14-14.

It wasn’t enough.

Gonzalez returned Prep’s kickoff 47 yards ­into St. John’s territory. Minutes later, Horgan delivered his winning 18-yard keeper.

“I was really proud of how we hung in there,’’ Adamopoulos said. “I’m happy right now.’’

Prep opened the scoring late in the first quarter when Yarin connected with senior Hayden Rockett on a 37-yard fade.

Owen Pence can be reached at owen.pence@globe.com.