Until last weekend, South Portland had never won a volleyball playoff match.

Now, the surprising Red Riots are headed to the Class A state championship match.

South Portland, the No. 5 seed, upset top-seeded Deering on Wednesday night, sweeping three sets by scores of 25-22, 25-23 and 25-10.

South Portland (11-6) will play second-seeded Scarborough at 7 p.m. Friday at Deering.

“I told the girls if they dig deep and fight and play defense, they could play with any team out there, and we did that tonight,” South Portland Coach Nicole Kane said. “We played as a team. We didn’t let balls drop, and I’m beyond proud of these girls. We stayed up, and we didn’t let anything bring us down.”

South Portland made far fewer mistakes than the Rams.

“South Portland played great volleyball and they deserved to win,” Deering Coach Larry Nichols said. “They took care of the ball (and) we didn’t. We didn’t do what we needed to do.”

“We can play better than we played tonight, but you’ve got to give credit to (South Portland),” Nichols said. “They came in and did their job.”

Deering (14-2) swept South Portland in their only regular-season match early in the season.

“We didn’t have a good service game that (night) and (Deering) beat us,” Molly Mawhinney said. “We were on our ‘A’ game tonight.”

“Serving was huge,” Kane said. “We definitely have been working on that a great amount of time. I’m really impressed with the fact we have six solid servers. There’s not somebody that goes behind the line that I get nervous about.”

Mawhinney put away a game-high 18 kills to key South Portland’s solid net play. She frequently found just the right spot in the opposite court to place the ball.

“When Molly didn’t have a blocker on her, we knew we had to feed her,” Kane said. “We knew which hitters could get the job done.”

“I just look for open spots on the floor,” she said. “Before I go up, I look to see where the openings are. (Deering plays) a very short defense, so I was able to go deep to the corners most of the time.”

In the first set, the Riots scored seven consecutive points off Grace Rende’s serves to pull into a 19-19 tie. The set was tied two more times before South Portland scored the final three points to close it out.

Deering rallied from a six-point deficit in the second set to make it 23-23, but Rende won the set for the Red Riots with an ace.

South Portland then started the third set by building a 9-0 lead off Ashlee Aceto’s serves. The Riots scored nine of the final 12 points to end the match.

“The girls don’t give up on themselves,” Kane said, “and this is the time not to give up on yourself. It’s really important that they don’t go flat.”