Whether it was the injuries or the frigid Cambridge air, Harvard came out that in the second half and gave up a goal 10:18 in on a two-person break-away.
Yale missed a chance to tie it less than three minutes later, as sophomore Amy Porter's shot sailed several feet over the Harvard net.
"We got a little lackadaisical and I think it's a function of being young," Coach Tim Wheaton said. "We're not playing for 90 minutes as intense as we should be."
But the Crimson Retaliated to go up 3-1 and when the Elis made it 3-2, Harvard scored immediately after.
Only 6:18 after Yale cut the score to 2-1, junior Reena Lawande chipped a pass ahead to senior Libby Eynon. Eynon made a 180-degree turn and ripped a bullet through Haist's hands from five yards out and in.
And 2:54 after the score became 3-2, Gudeman threaded a perfect pass that caught freshman Lindsay Minkus in full stride. Minkus went in alone on Heist and scored up high to end the scoring with 18:11 to go.
"We have a lot of depth," Wheaton said. "We said at the beginning of the year that everybody on our team can play, and everybody did."
Besides beating its most-hated opponent, Harvard kept pace with Brown, who is still undefeated in the Ivies. Should the Crimson win its final three Ivy games, then it would be league, champion.
But before its next Ivy match at Princeton on Saturday comes a tilt against New Hampshire tomorrow. It will take place at at Ohiri Field at 3:30.
"Beating Yale meant a lot to everybody," Lawande said. "We're on track to do really well in the Ivy League."