PORTLAND — Missed free throws by Thornton Academy at the end of regulation, then key plays by Jorden Mitchell and Aubrey Folger in overtime helped No. 3 Marshwood escape with a 51-49 win over the sixth-ranked Trojans in a Western Class A girls’ basketball quarterfinal Monday at the Portland Expo.

Mitchell’s three-point play put the Hawks (16-3) ahead to stay after Folger tied the game early in overtime. Marshwood, making its first tournament appearance since 2009, advances to the semifinals on Wednesday.

Thornton (11-9) was 3 of 8 in the fourth quarter and 1 of 4 in overtime at the free-throw line, including missing five of their final six attempts.

With the Trojans up 39-31 with the ball in the fourth quarter, it looked like they wouldn’t have to worry about making free throws. But Folger picked off a pass and went in for an easy layup, sparking Marshwood’s comeback. She also stole an inbounds pass and made another layup with 25 seconds left in regulation for a 44-43 lead.

Freshman Kaitlyn McCrum had a chance to win it for Thornton when she was fouled on a baseline drive with 5.7 seconds to play. She front rimmed the first free throw but, after a Marshwood timeout, coolly drained the second to tie the game.

Thornton then threw on a surprise press, and sophomore center Olivia Shaw picked off the inbounds pass and was fouled. She missed both free throws, and the game went to overtime.

“I know everyone’s going to want to talk about the free throws but bottom line, we’re not even at the Expo without these young kids,” Thornton Coach Eric Marston said. “It wasn’t the free throws. It was us not executing down the stretch.”

Folger finished with 22 points for Marshwood. Mitchell recovered from a shaky start, scoring 13 of her 15 points after halftime.

Marshwood Coach Lee Petrie, discussing the late comeback and the effort needed in overtime, joked that the Hawks had won the game, “just like we drew it up.”

“You know what? It is like how we drew it up. Yeah, we drew it up a long time ago when these girls started playing together,” Petrie said. “We have a bunch of seniors that won’t let us lose, but I tell you, our junior Alli Schoff had the game of her life today, stepping up as a junior.”

Schoff and Jillian Gori came off the bench to team with Folger at the top of the Hawks press when it was most effective.

Schoff was also 5 of 6 at the free-throw line.

Thornton was led in scoring by McCrum (15 points on 6-of-7 shooting), senior Meghan Agger (13 points) and Shaw (10 points).