With two outs in the bottom of the sixth, the game tied and the series on the line, Lincoln Broussard stepped to the plate.

The senior swung. The ball cleared the wall and struck the roof of the multipurpose building beyond it.

Grand slam. 10-6 Niceville.

The blast sealed a 10-6 Game 3 victory Sunday and a regional semifinal series win over Mosley, sending the Eagles to the Elite Eight for the second straight year and to the doorstep of their first Final Four appearance since 2008.

“I’m just so happy and excited for Lincoln to have that moment,” Niceville head coach Justin Bruce said. “We needed some runs, and he came through in a big moment for the team.”

Broussard said the at-bat carried the weight of a heated series.

• “I was just excited,” he said. “It’s been a heated matchup. I was really excited and hyped to seal the game with that at-bat.”

Game 1: Mosley 5, Niceville 1

Originally scheduled for Friday, Game 1 was pushed to Saturday at 5 p.m. after thunderstorms swept through the area.

Ethan Thomas got the start for Niceville, opposite Louisville commit Ryan Harless for Mosley. Thomas allowed two early singles but escaped without damage, and Niceville struck first on a Deacon Avery home run.

The Dolphins answered with five unanswered runs. In the second, Thomas walked Derek Ortiz and Jacob Oakes, and an error allowed Brayden Nelson to reach and Ortiz to score. Xavier Demro and Brady Lee reached on fielder’s choices before Harless doubled them both home for a 3-1 lead.

• CJ Harris singled in the fifth and scored on a string of errors. Harris came home again in the seventh on more Niceville miscues to close out the 5-1 win.

Game 2: Niceville 6, Mosley 2

Originally part of a Saturday doubleheader, Game 2 moved to Sunday at 1 p.m.

Aahron Geleta got the nod for Niceville, with Carter Payne starting for Mosley. The Eagles set the tone early and never looked back.

Thomas opened the scoring in the second on a series of errors. In the third, CJ Bolden doubled and scored on a sacrifice fly from Remington Crum.

The fifth fell apart for Mosley. Crum reached on an error by Brantley Davidson, Ryder Hodgkinson was hit by a pitch and Jake Morvay singled. Crum scored on another error as Thomas drew a bases-loading walk. Payne was pulled for Davidson, who walked Jake Buis to score Hodgkinson. Boston Browning, batting for an injured Colton Cook, lifted a sacrifice fly that scored Morvay. Broussard followed with an RBI single to make it 6-0.

Demro hit a two-run homer in the sixth to cut it to 6-2, but Geleta closed the door, going the distance on two hits with five strikeouts.

• “Aahron Geleta has been begging for the baseball all year,” Bruce said. “He’s done nothing but come out and try to help this team win.”

Game 3: Niceville 10, Mosley 6

Morvay started for Niceville, with Lee on the mound for Mosley. Mosley jumped out early.

Morvay allowed a Demro double followed by three straight walks, the last forcing in a run. Ortiz added an RBI single to make it 2-0 Dolphins.

Niceville answered immediately. Crum and Hodgkinson singled, and Morvay reached on an error by Harris that scored both runners to tie it.

In the third, Morvay singled, Thomas walked and a Cook sacrifice fly scored courtesy runner Quentin Saviola. Lee was pulled for Peyton Williams.

Mosley responded with a Demro two-run homer that also scored Davidson. Morvay was pulled for Sean Britton, who steadied the inning. The Eagles tied it back up when Crum walked and Morvay doubled him in.

Mosley retook the lead in the sixth. Demro singled, Harless doubled him home and Oakes scored on a wild pitch — a controversial sequence in which Niceville argued interference. The umpires disagreed. Britton was injured on the play, and Broussard came in to pitch.

The Eagles’ bats came alive in the bottom of the sixth.

Avery singled. Crum singled him in. Hodgkinson singled, and Morvay singled to score Crum and tie it. After a sacrifice bunt and a strikeout, Cook walked to load the bases.

• Then came Broussard, the slam and the roof of the multipurpose building.

Bolden followed with a single, and Williams was pulled for Jake Yeats. Avery flew out to end the inning.

In the seventh, Broussard retired Payne on a groundout and Davidson on a popout, hit Nelson with a pitch and struck out Demro to end it.

What’s next

Niceville will face Lincoln in the Elite Eight, a rematch of last year’s regional final. Lincoln advanced past Chiles, the 5A state title favorite.

The Eagles beat Lincoln 11-3 in Tallahassee on March 18, but Bruce said the Trojans have improved since.

“Lincoln’s a well-coached team. They are a really good team,” Bruce said. “But I’m glad we’re getting them at our place. I hope that we can battle and find a way to win that.”