Colleen Slattery scored on the second penalty corner as top-ranked Cheverus held off a valiant eighth-seeded Westbrook 2-1 on tie-breaking penalty corners in a Class A South quarterfinal Tuesday at Deering High.

“I was down there where I was supposed to be, and Sophia (Pompeo) sent it where she should have,” Slattery said. “I knew it had to go in that goal.”

Westbrook (8-8) never threatened on its second penalty corner. Cheverus (13-2) will meet fourth-seeded Sanford (12-2-1) in the semifinals.

“These kids played out of their tree and stepped up,” Westbrook Coach Beth Murphy said. “You can’t be disappointed in the way the kids performed. They didn’t quit.”

Both teams had chances in the first overtime, but Westbrook got the best. Stags goalie Deidre Sanborn made a sitting save in the middle of the period and stopped a three-on-one in the final minute.

The Stags scored first when Hannah Abbott collected the ball off a scramble and put it in. Freshman goalie Kimmy Goddard made a number of saves but Cheverus kept the ball in the offensive zone.

After Cheverus’ goal with about 23 minutes left in regulation, Westbrook tied it 12 seconds later. Danielle Breuning took a long pass from Abby St. Clair and fired it in.

“It was just a mental breakdown that is unacceptable in the playoffs,” Cheverus Coach Amy Ashley said. “The most dangerous minute on the field is the minute after somebody scores, and we talked about it on the field. I guess I have to coach them and better prepare them for that next time.”

Neither team found much room in the middle of the field. Pompeo and Westbrook’s Tianna Moore were stymied by defenders when trying to pass or dribble.

The scoreless first half found each team trying to establish its offense, but the defense for both sides was stout. Cheverus and Westbrook attempted two penalty corners in the half, but none resulted in quality chances.

“Their defense did an excellent job of shutting down our offense,” Ashley said. “We should have had more chances but we couldn’t get it past their last line (of defenders). We need to execute better.”

In the middle of the first period, the Stags applied sustained pressure. Emily Michaud and Abbott had Westbrook on its heels, but the defenders snuffed out a number of crossing passes and shots.

Cheverus got its only quality opportunity off a penalty corner. After the inbounds, the ball was knocked around by both teams until it found its way to the cage. Goddard was out of position, but Camryn LaPierre got her stick down and saved the goal.

Westbrook’s best chance of the half came on a shot by St. Clair. The ball stayed in the offensive zone and was batted around before Cheverus cleared and rushed the other way.