SPRINGFIELD, Mass. — Ever since the fourth grade, Meghan McGuinness has immersed herself in the science of the free throw. It started with her AAU coach in Central New Jersey, continued through high school and accompanied her up to Monteagle Ridge. And it’s her passion for a facet of the game too often understated that has Niagara heading into the Metro Atlantic Athletic Conference semifinals and a meeting with dynastic Marist.

McGuinness, a sophomore guard, was the calming influence for the Purple Eagles (15-15) at a time when they were in dire need of a steadying hand. An 85 percent free throw shooter, she went 6 of 6 from the line over the final 2:10, secured a 59-54 quarterfinal victory over fourth-seeder Rider and saved Niagara from squandering the entirety of a 17-point lead.

“She’s clutch there,” said Lauren Gatto, Niagara’s all-conference forward. “She goes to the line with the confidence as if she’s just in practice and she knocks them down every time.”

“Since like fourth grade my AAU coach, I was on the Central Jersey Hawks, and she was like a fantastic shooter and just taught me how to shoot, form shooting, and we would just do form shooting all the time, between every drill,” McGuinness said. “All through middle school, high school, I’ve always done that, just stayed after practice throwing in free throws.”

It appeared Niagara would have no need for McGuinness’ expertise at the line, at least not with the game hanging in the balance. They overcame foul trouble that put Gatto on the bench for 13 minutes and built a 25-19 halftime lead. The advantage swelled to 41-24 as Gatto (14 points) returned and tormented Rider (15-15) from inside and out.

“No player wants to ever sit on the bench but I have complete confidence in my teammates,” Gatto said. “They’ve proved they can play with or without me so I think that was just the most important thing was me keeping the right mind-set knowing I’d come back in and play the second half.”

On the verge of being blown away, Rider summoned its pride and its press and ran off 12 straight points, drawing within five on two free throws by MyNeshia McKenzie (game-high 22 points) with 7:44 left. That’s where McGuinness (team-high 15 points) stepped in, cashing two free throws with 2:10 left, two more with 1:41 remaining and the final pair to put the game away with 1.9 seconds on the clock.

“Give credit to Rider for that press, they were really intense pushing up on us,” said Niagara assistant coach Corinne Jones, the primary coach after Kendra Faustin gave birth on Feb. 27. “We could have done a better job going to the ball, being a little more strong with it, advance it a little sooner, but again the credit goes to Rider for staying in there.”

Niagara shot 36 percent for the game (18 of 50) and persevered despite committing 20 turnovers. Rider made 16 of 58 from the field (27.6 percent). The Purple Eagles as a team went 17 of 19 from the foul line.

Awaiting the Purple Eagles is the Herculean task of facing Marist, winner of the last seven MAAC titles. Niagara fell in overtime to the Red Foxes in last year’s semifinals but dropped this season’s two meetings by margins of 20 and 27.

“It’s tournament time,” Gatto said. “Nothing that happened in the regular season really matters anymore. So now, going into this game in pretty much the same position as we were last year against them, I think we know we’re completely capable of beating them.”

Niagara’s 15 wins are the most since it won 17 in 2004-05. That was also the last time the Purple Eagles beat a team three times in a season, as it did Rider this year.