Defending champions aren’t supposed to be underdogs, but that’s how the Kennebunk High girls viewed themselves in the Class B lacrosse state championship game.

They even came up with a slogan to address naysayers who noted the 11 graduated seniors and only three returning starters: Prove them wrong.

On Saturday morning, the Rams did just that with a 5-4 victory at Fitzpatrick Stadium over previously unbeaten Yarmouth.

“There’s nothing more satisfying than coming off this field, having nobody believing in you except for the girls around you, and proving them wrong,” Kennebunk junior midfielder Hallie Schwartzman said.

The Rams (13-2) never trailed against a Yarmouth team (15-1) that had beaten them 7-3 on a rainy day in late May. Beneath overcast skies, Kennebunk put into action lessons learned from the earlier loss, showing more patience on offense and clogging the middle on defense.

“We studied the film when we played them last and we looked at all the things that we needed to fix,” said Kennebunk senior goalie Mallory Burchill, who made five of her seven saves after intermission. “I think they were frustrated because we figured them out a little bit. They tended to plant people in the middle and we figured out how to work around that.”

Maran Oakman played the backer position and roamed the perimeter of the 8-meter arc, giving Kennebunk an extra layer of defense against Yarmouth attackers and preventing entry passes in front of the net.

“I’m not assigned to a spot and no cutters are my responsibility,” Oakman said. “My only responsibility is to be behind the ball and pick off the pass going into the (middle). It’s a frustrating defense because it’s new, so a lot of people don’t know how to beat it.”

Kennebunk jumped to an early lead behind goals from Erin Gorton (free position) and Leah Dumas (assist from Briannagh Beaudette). Yarmouth responded with a transition goal from Ella Antolini, her first of three.

Dumas curled from behind the net to make it 3-1. Gorton converted a feed from Schwartzman to give Kennebunk a 4-1 lead.

“The backer is not something we see a lot, and it flustered us initially,” said Antolini. “With Eva (Then), Eliza (Lunt) and Cory (Langenbach), I confidently say they’re the strongest drivers in the state. With that backer, they completely take that away. They essentially double the ball. Not a tight double, it just prevents us from getting the feed through, and it prevents the drive from the top.”

Antolini converted from free position to make it 4-2 at the half, but Gabby Fogg scored early in the second half to put Kennebunk up 5-2. Only the crossbar prevented Kennebunk from padding its lead, not once but twice.

Greta Elder gave Yarmouth life with 8:38 remaining by flipping in a feed from Meredith Lane. Two minutes later, Antolini capitalized on one of Kennebunk’s 13 turnovers to make it 5-4.

For the remaining six minutes and change, Kennebunk tried to run out the clock and the Clippers pressed for the equalizer.

“We knew we didn’t need to shoot,” Kennebunk Coach Annie Barker said.

A Langenbach steal with 2:30 remaining gave Yarmouth a chance to tie, but the Kennebunk defense held. Callie Decker stole it again with a minute left and Yarmouth called time with 27 seconds left to set up a final play.

Yarmouth Coach Dorothy Holt directed the ball to go to Elder, who would pass to Then, who would drive net. Instead, an errant pass behind the goal short-circuited the play. The title remained with Kennebunk.

“Coming from behind is tough, but we rallied,” Holt said. “We showed we could. We just needed five more minutes.”