LEWISTON — In the blink of an eye, Emily Harper ended a defensive stalemate between top-seeded Monmouth and fourth-seeded Maranacook in a Class C South girls soccer semifinal on Saturday.

Harper scored the only goal the Black Bears needed to hand the Mustangs their first loss of the season in a 1-0 Maranacook victory at Don Roux Field.

“She just got loose once,” Monmouth coach Gary Trafton said. “They put her at midfield, and we just lost sight of her for once.”

Harper spent much of the first 64-plus minutes shooting at the goal, but either missed just wide or was stopped by Monmouth (15-1) goalie Emma Johnson. Even getting those type of opportunities was difficult, with Monmouth senior defender Libby Clement right with Harper any time she got the ball at or near her feet.

“(Libby) gets zero recognition, nothing, and she’s certainly an All-Stater, for sure,” Trafton said. “I mean, she anchors that back and she runs down balls that you don’t think she’s going to run down. She’s a solid, solid player.”

“She’s a really amazing player,” Harper said. “That was a lot of work. I think definitely moving positions helped, though.”

Clement, or any Mustangs defender, for that matter, was nowhere near Harper when she came running onto a failed Monmouth clear attempt out of the box and drove home the game-winning goal past Johnson with 15:13 to play.

“I just remember creating a little bit of an opening and just shooting it,” Harper said. “I didn’t know if it was going to in or not.

“It felt really good.”

At the other end of the field, the Black Bears (12-2-3) defense did a solid job of stymieing Monmouth strikers Audrey Fletcher and Alicen Burnham, whose crosses were more dangerous in the game than any shot attempts.

“We have kids that have marked all year on different kids. We’re used to it and we did a great job,” said Maranacook coach Travis Magnusson, highlighting Ella Schmidt and Anna Drillen. “(Fletcher and Burnham) are really good players, so it takes a lot to shut them down. It’s a team effort. But our bread and butter is our defense. We’ve talked about it all year. So in back-to-back big games (including in the quarterfinals against Waynflete), 1-0 wins is kind of what we’re looking for.”

Trafton said the Black Bears’ defensive game plan wasn’t fancy, but it worked.

“They did just what I knew, beat the (heck) out of you,” he said.

The Mustangs had more shots on goal than the Black Bears in the first half, 4-3, and had two good looks early in the second half, but couldn’t put any past Maranacook backup goalie Anna Erb.

“We had our chances,” Trafton said. “I knew we wasn’t going to get a whole lot, but we got enough chances to put some goals in, so …”

Erb filled in for starter Skye Webb, who couldn’t play keeper due to injury.

“I think a lot of teams would have shut down when you have your All-State goalie three days before not know if she can play or not. But we didn’t. We didn’t miss a beat,” Magnusson said. “Just a number of people stepped up. So it’s a testament to our mental toughness, for sure.”

Erb made six saves for the shutout, while Johnson turned away nine for the Mustangs.