Smithtown West’s girls lacrosse team had gotten used to being the underdog. That changed this season.

With an 11-8 win over host Ward Melville on Thursday night, the Bulls clinched the top seed in the Suffolk I playoffs. Mackenzie Heldberg, a five-year varsity standout who will play at Johns Hopkins in the fall, had never experienced being at the top of the standings.

Now the Bulls are second to none.

“We’ve always been kind of the underdog the past few years, and I think it’s just awesome saying that we’re finally No. 1, the top dog,” she said.

Heldberg willed an offense that struggled to control its passes and maintain possession, scoring five goals and chipping in two assists. She scored the Bulls’ final three goals.

She also ignited a 3-1 run to end the first half. She scored 13:35 before the break, then assisted Grace Langella twice before Ward Melville’s Kaitlin Thornton scored to make the score 7-4.

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Langella scored again to begin the second, her fourth and final goal. Kerri Liucci put Ward Melville (11-4) back on the board before Heldberg scored her first of three straight with 15:06 remaining.

Smithtown West (13-2) led 11-6 after Heldberg’s final goal with 7:07 to play. It came time to ice the clock and preserve the win, but the Bulls struggled to pass accurately, giving the Patriots a window to mount a comeback. Nicole Liucci and Alexi Reinhardt had the game’s final two goals with less than two minutes remaining, but the Patriots’ comeback fell short.

The Bulls’ offensive struggles put goalie Marisa D’Amico in a tough position, but she quickly put to rest any hopes of an upset. She made 12 saves — nine in the first half — and credited the defense for her success.

“Everyone makes mistakes,’’ D’Amico said, “but I think our defense was able to handle the pressure and control it.”

Crease defense was key in her success, and coach Carie Bodo praised Jessica English, Katherine Aldrich and others for their fine work in front of D’Amico. “When our defense plays tight in, she can make any saves because the defense made the best angles for her,” Bodo said.

With D’Amico leading the defense and Heldberg providing a steady presence on offense, the Bulls are poised for a deep postseason run.

And they definitely won’t be considered underdogs.