PORTSMOUTH — Lots has been tried. Not much has been true.

For two-plus years now, and for a couple decades back in a previous era, Portsmouth High School football coach Brian Pafford has turned over countless rocks in his preparation for games against Exeter, without finding the key to unlock a win.

“I think we’ve tried everything over the last (three) years,” he said. “Some things work and some things don’t. I think our guys have bought into what we want to do; the question is, can they execute it? They’re so good defensively and they’re coached so well. You try to take what they give you and the problem is they close that down fast, too.”

Portsmouth-Exeter has always been a little brother/big brother relationship, the bigger school with the bigger roster and loads of recent success having its way against the thinner Clippers.

The teams have met three times since Portsmouth rejoined Division I in 2014 — a competitive, 28-17 loss in 2014; a 35-6 loss in that season’s East Conference championship game, where the Clippers felt they left all kinds of points on the field; and last year’s non-competitive, 43-14 blowout.

“We know it’s going to be a tough game,” said senior wide receiver/defensive back Shon Parham. “Exeter’s 4-0 and always a great program. We’re just going to try to come in, play our best and execute. I think we’ll do fine.”

It’s an anticipated game because the Clippers (3-1) come in with a couple of quality wins under their belt, an offense that’s averaging better than 33 points a game — moving the ball both in the air and on the ground — and a growing confidence that they can be one of the eight teams to qualify for the Division I playoffs.

“The run game has been good to them,” said Exeter coach Bill Ball. “It was really good for them against Keene. It was really good against Winnacunnet (a 22-6 win in Week 3); they finished the game, they closed it out.

“You can’t just load up, you’ve got to play. They make you play sideline to sideline and endline to endline. They stretch you horizontally and they stretch you vertically, and if you get too soft they’re going to run it right over you, so you’ve got to play.”

In Exeter, they’re facing an offense that has moved the ball against everyone it’s played, primarily on the ground behind backs Cam Flanagan, Brayden Lowery and Zach Knight. Quarterback Kyle Ball has only attempted a handful of passes, but the third-year starter has a track record of making big completions when his team needs them.

“We’ve just got to be tougher than them,” said Clippers senior defensive end/running back Ben Barba. “Stay low, do our job and be tough, that’s what we have to do.”

Offensively, where the Clippers have struggled the most against Exeter is in the red zone, where the amount of open space they can spread their playmakers to shrinks.

“We’ve got to move the ball and use the space when we have it,” said Pafford. “It’s going to be tough for us to score from inside the 10-yard line. You saw that in the playoff (in 2014). How many times did we have the ball inside the 5 and didn’t score? Three times, I think.”

Quarterback Cody Graham leads all area passers with 818 yards (61 percent), with seven touchdowns and six interceptions. His targets include Shon Parham (22 catches for 345 yards), Christian Peete, Jared Padgett, Hunter Adams and Aidan Moore.

“They’ve got really good receivers,” said Exeter defensive back Ben Palmer. “They’ve got really good feet, good hands. They can run good routes. We’re going to have to really work this week. We’ve got to get our checks down.”

Portsmouth knows its margin for error is slim. Its broken its game plan down into smaller chunks of execution — force the Blue Hawks to punt twice each half, don’t give up big plays and don’t turn the ball over.

If the Clippers can do all that? Then maybe, for one night, they can reverse these established roles.

“We continue to prove people wrong,” said Barba, “and I think we can do it again.”