The winner moves on to face either St. Bonaventure or San Dimas in a second-round game at 3:15 p.m. Tuesday.
Tuesday's playoff win was the fifth straight victory for Laguna, which won for the 11th time in its last 13 outings.
"Steven loves those moments and the entire team believed he was going to come up clutch for us," Laguna Coach Mike Bair said of his catcher, who was an All-Orange Coast League player as a freshman. "As soon as the ball cleared the fence, we went crazy in the dugout. It was a great moment."
There were several great moments during Tuesday's comeback win for the Breakers, who trailed, 3-0, after half an inning. They pulled to within 3-1 at the end of one and still trailed, 4-2, through three. They drew even after scoring single runs in the fourth and fifth innings.
"We got down in the first and just chipped away all game long," Bair said. "We were clutch today and fought strong for seven innings. A great team win."
Harrison wasn't the only Breaker to come up big offensively. Senior Alex Iannotti also homered and had two runs batted in during a three-for-three performance. Sophomore Preston GrandPre doubled and went two for three with an RBI, sophomore Grant Wilhelm had two hits, juniors Blake Hester and Robbie McInerny both singled and junior Larry Stewart had an RBI.
Laguna outhit the Jackrabbits, 10-6.
Wilhelm started on the mound for the Breakers, but it was Kurt Rebone (4-2) who picked up the win. The junior didn't allow a run and struck out four in 2 2/3 innings.
The Breakers concluded regular season play May 10 and scored a 16-2 Orange Coast League win over host Saddleback. Harrison also homered in that game, doubled and drove in two runs in a three-for-four game. Junior Jackson Rees struck out five and ran his record to 6-3.