South Portland won two intense regular-season battles. Thornton Academy took the game that mattered most.

Thornton Academy made a series of big plays to get to overtime, then stole the ball repeatedly in the extra session to end South Portland’s bid for an unbeaten season, earning a 61-55 victory in the Class AA South boys’ basketball final Saturday night at Cross Insurance Arena.

Thornton (18-3) will meet Edward Little (19-2) next Saturday evening in the state championship game at CIA. In the second game of the regular season, Thornton beat Edward Little, 66-49, in Saco. Thornton’s last state title was in 2009, when it defeated Edward Little in the Class A final.

Trailing by four points with less than a minute remaining in regulation, Thornton got a huge 3-pointer from Costa Gikas, who was fresh off the bench. South Portland’s Geremi Baez made one free throw but missed the second with 12.7 seconds left. Thornton’s Payton Jones grabbed the rebound, weaved through traffic, nearly lost his dribble, then dished to Will Mitchell for an uncontested layup that tied the game at 44-44 with 2.5 seconds remaining.

“We drew up a play and I kind of lost the ball at the end coming off a screen. I jumped and kind of blurred my eyes a little bit and saw Will Mitchell’s head and I thought, ‘I’ve just got to make (the pass) there and hopefully he makes it,'” Jones said.

In overtime, Jack Pyzynski came up with two steals to set up baskets by Jones and Colby Lands. A Kobe Gaudette drive made it 50-46.

“We were told just to not foul, and I saw the opportunity and went for it,” Pyzynski said. “We’ve played real good defense the whole year, and I knew my guys had my back if I didn’t get the steal.”

From there, the Trojans continued to force turnovers that led to eight free throws and a 58-46 lead with 28 seconds to play.

South Portland’s Pamba Pamba made three 3-pointers in the final 20 seconds.

Jones, who had to leave the floor briefly in the third quarter, led Thornton with 19 points and was named the regional’s outstanding player. Pyzynski scored 18 points, and Mitchell got nine off the bench while helping solidify Thornton’s rebounding with center Dylan Griffin hampered by foul trouble much of the game.

“It’s a complete team and they didn’t quit, and that’s a good thing,” said Thornton Coach Bob Davies.

South Portland (20-1) made just 1 of 7 free throws. Pamba scored 20 points but was the only starter with more than six. Hunter Owen got 14 points off the bench.

South Portland won the regular-season games, 68-65 in overtime at home and 60-50 in Saco.

“Thornton’s an awesome team. It was a 50-50 game every time we played them,” said South Portland Coach Kevin Millington. “It was the same tonight, and they won. They were better than we were tonight.”

Pyzynski said the losses helped Thornton prepare for the regional final.

“It just made me super mad. The first one, we came up a couple of free throws short of just icing it,” Pyzynski said. “I just wanted to beat them so badly, and it just fueled all of us.”

South Portland led the entire first half and was up 23-18 at halftime behind eight points and seven rebounds from the 6-foot-5 Owen, who has signed a national letter of intent to play baseball at Vanderbilt.

Thornton took the lead for the first time on a 3-pointer by Pyzynski with about 10 seconds left in the third quarter.

South Portland scored the first six points of the fourth, but Pyzynski and Jones each finished at the rim to make it a one-point game, setting the stage for a tense finish in front of a large, boisterous crowd.