On three crucial occasions, Yale gave the Harvard field hockey team a key into its backfield.

On all three occasions, senior midfielder Shelley Maasdorp was right there to open the door.

The No. 17 Crimson (8-4, 4-0 Ivy) relied on a hat trick from Maasdorp to recover from a sluggish first half and send the Bulldogs (5-6, 1-3 Ivy) home from Jordan Field with a 3-2 loss.

Maasdorp’s trifecta was comprised solely of penalty corners, in which the Crimson possessed a distinct advantage for the game. Harvard drew 11 penalty corners in the contest to the Bulldogs’ four.

Saturday’s goals were just numbers 10 through 12 for the Crimson’s leading scorer.

“Today was a fight. It was a struggle,” Maasdorp said. “[But] we executed.”

Harvard broke a 2-2 tie with less than four minutes left in the game when junior midfielder Jen McDavitt passed to captain midfielder Kate Gannon, who set up Maasdorp for the winning goal with one of her three assists.

“Execution on the corners was all we needed,” Gannon said. “Once we started scoring on them, it fed off itself.”

To its credit, however, Yale played much of the first half with a fire that Harvard was hard-pressed to quench.

Less than four minutes in, the Bulldogs’ Meredith Hudson caught Crimson netminder senior Aliaa Remtilla out of the goal, exploiting the opportunity for an unassisted score.

As the game dragged into a defensive dogfight for the subsequent 25 minutes, Yale held both the 1-0 lead and the momentum of the game.

But down by one with just over five minutes left in the first half, the long-dormant Crimson struck. Junior midfielder Jen McDavitt forced an Eli penalty while driving to the net, and on the corner, Gannon passed to Maasdorp. Deftly, Maasdorp feinted a shot before taking her time, pausing in a moment of repose and firing a bullet to the back of the net to tie the game.

“I think they came out with a lot more intensity than we did in the first half, and that was something we recognized at halftime,” Gannon said. “[We] made a conscious decision to change that.”

Enabling Harvard’s ultimate second-half success on offense was a solid defensive foundation. The Crimson allowed the Bulldogs to take only six shots in the second half, compared to 10 in the first frame.

“I think there was definitely a momentum shift,” Gannon said. “Once we got a goal, we had the confidence to keep going with it, and that was huge.”

Yale seized the lead again halfway through the second half, however, when Harriet Thayer fed the ball to Sarah Driscoll, who slipped in around the outside, availing herself of a momentary lapse in the Harvard defense. But before the Bulldogs could establish control of the game, the Crimson began its surge behind Maasdorp’s shooting to close the door.

On a penalty corner opportunity, McDavitt passed to Gannon, who trapped the ball to enable Maasdorp to send one to the back of the goal for the tie.

Minutes later, Maasdorp would break the stalemate with the game-winner, preserving Harvard’s elite status as undefeated in the Ivy League.

“To be unbeaten in the Ivies still, to hold on to that record is huge,” Gannon said.

The Crimson will welcome No. 12 Boston College to Jordan Field at 7 p.m. on Wednesday night.