BROOKVILLE, N.Y. — Jake Mastillo knew he had at least driven in the game-tying run. As it turned out, Mastillo did much more.

Mastillo's one-out grand slam on a first-pitch fastball in the bottom of the 11th lifted the LIU baseball team to a 9-6 walk-off win against Merrimack in Friday's series opener.

Mastillo, a redshirt junior who transferred this season from Division II Lock Haven, now has 11 home runs with the Sharks.

With his heroics, he entered the top 10 in Division I program single-season history and joined Atlanta Braves draft pick EJ Exposito (2022) as the only two LIU D-I players to reach that long ball total since Joe Zeccardi had 13 in 1999.

Mastillo had been homerless in his last 14 games since a two-homer outburst at Stonehill on March 24.

"I was trying to be selective, because they had been pitching me low and away," Mastillo said. "Honestly, a first-pitch fastball in an at-bat, you really can't turn down the opportunity. The intention was to score the runner on third. I wanted to give our guys a shot to keep playing this ballgame. I couldn't find a better group of guys to have probably the coolest moment of my entire life with."

Initially, Mastillo thought the shot to left field would result in a game-tying sacrifice fly, which in itself made him content. Then it cleared the fence.

"I knew at the least he was scoring from third base and the game was tied. And then I saw it go over and that moment kicked in," said Mastillo, who was mobbed by teammates after crossing the plate.

LIU improved to 9-7 in the NEC.

Ryun Cross picked up his first LIU win, but the relief heroics primarily belonged to Shane Tucker. He struck out the side in a tie game in the top of the ninth and did not surrender a hit in two scoreless relief innings.

Starter Alec Huertas logged a season-high-matching eight innings and struck out a career-high-matching 10 batters for the second straight game.

LIU and Merrimack continue the series at 1 p.m. on Saturday.