After clanging his first shot of overtime off the post in a Maryland 4A/3A lacrosse semifinal against Bel Air on Friday, South River’s Ben Chisolm wondered if it would be the last attempt of his junior season.

Chisolm, who has committed to Maryland, had to endure some anxious moments with his team on the defensive end but his patience paid off.

Sixth-ranked South River will play in its third state final in four years after Chisolm’s sixth goal of the game — a blast off a quick restart early in the second overtime period — lifted the Seahawks to a 10-9 win over the Bobcats at Franklin High in Reisterstown.

The Anne Arundel County champs will try to close out their second perfect season in four years in next week’s state final at UMBC against the winner of Saturday’s Churchill-Westminster semifinal.

“It was hard there in the first overtime,” Chisolm said. “I was thinking, ‘We worked way too hard to let it go like this.’ ”

South River (19-0) handled Bel Air, 15-3, in a nonleague regular season meeting in April.

But the Seahawks spent most of Friday night chasing the South region champs.

Chisolm’s heroics kept his team within a goal entering the fourth quarter. Despite the full attention of the defense, he managed to use his speed to create chances on the perimeter that he usually finished with a leaping laser on cage.

The game-tying goal in the fourth was one of his best highlights when he spun out of a double team and buried a left-handed shot.

“You’ve just got to believe in your team,” Chisolm said. “You can’t ever think that you’re out of it.”

The Seahawks dominated possession in the waning minutes of regulation but didn’t score. Bel Air (11-6) almost capitalized in the final seconds but sophomore Nick Marcelino made a save to send the game to overtime.

Neither team scored in the first four-minute overtime; Chisolm came closest with his shot off the post.