WINTHROP — A year ago, Monmouth Academy senior Avery Amero was trying to throw strikes for the junior varsity team. Saturday, he turned in the performance of his life at the varsity level.

Monmouth coach Eric Palleschi called upon Amero with two out in the first inning and he responded by not allowing a run the rest of the way. He had plenty of help from his teammates, who pounded out 16 hits and rallied from four runs down.

The final: Monmouth 8, Winthrop 4.

The sixth-seeded Mustangs (11-7) advanced to the Class C South regional final Wednesday at St. Joseph’s College, where they’ll face Lisbon or Traip Academy. No. 2 Winthrop finished its season 11-7.

Monmouth had lost in the semifinal round the past three years, including last season when they entered the game unbeaten.

“Every single year we’ve come close and it’s just that one thing,” said Monmouth shortstop and four-year starter Hunter Richardson. “I’ve had nightmares since of just really trying to get past that. We were the underdog in this game and it felt good to … finally break through that wall of the semifinal.”

The Mustangs fell behind 4-0 in the first inning when starter Avery Pomerleau struggled with his control and was hurt by a couple of errors. Enter Amero, who relied heavily on a 12-to-6 curveball that kept the Ramblers off-balance.

“We’re pretty good with the straight fastballs, not so much with the curveballs,” Winthrop coach Marc Fortin said.

The Mustangs scored a run in the second inning off Winthrop starter Antonio Meucci and cut the lead to a run in the fourth on three hits as Greg Fay came on in relief. Both Meucci and Fay threw a number of curveballs as well and many of the Monmouth hitters took them the opposite way.

“We had a game plan,” Palleschi said. “We knew we had to stay back on the offspeed stuff and hit the ball on the right side of the field.”

The Mustangs took the lead with three runs in the fifth. After Nick Dovinsky walked and Travis Hartford singled, Amero boomed a triple over Maguire Anaszewski’s head in right field to make it 5-4 Monmouth. Amero scored on Corey Armstrong’s hit up the middle.

“I’ve been in a kind of a slump lately,” Amero said. “It definitely feels good to finally get one out there.”

The Mustangs added two in the seventh after Trevor Flanagan collected his fourth hit of the game and Mat Foulke bunted for a base hit to load the bases. Pomerleau drew a walk to force in a run and Richardson’s groudout scored another. A circus catch by Anaszewski in right off Amero’s bat prevented further damage.

The Ramblers rallied in the seventh on singles from Jackson Ladd and Bennett Brooks. Following an out, they loaded the bases when Matt Ingram was hit by a pitch. The game ended on an unusual note when Ingram was forced at second on Meucci’s ground ball and a double play was called due to interference on Ingram’s slide.

“He came up in front of Matty (Richardson),” Palleschi said. “We’ve worked on that for two weeks trying to get Matt to stay in there and throw through the runner and today he does it and it pays off.”

The Ramblers beat Monmouth twice in the regular season with Jacob Hickey on the mound, but because Hickey pitched in the quarterfinals, he wasn’t available Saturday.

“I thought we had a great year,” Fortin said. “I wish we were still playing.”

Armstrong, Hartford and Dovinsky each added a pair of hits for Monmouth.