Sam Hurster got open in front of the net with 4.7 seconds left and finished off the upset as Brown beat top-ranked host Cornell, 10-9, at Schoellkopf Field.
The Bears improved to 6-7, 2-3 Ivy League, while the Big Red dropped to 9-2, 4-1.
The loss ruined Cornell's Senior Day celebration and ended its national-best 15-game winning streak. It also dropped the Big Red a game behind Princeton in the standings heading into next weekend's showdown in New Jersey. The winner of that game will host the Ivy League tournament.
No. 3 Massachusetts 14, Hofstra 13: A four-goal fourth-quarter run and a caused turnover by Greg Rushing with 25 seconds left in regulation helped the host Minutemen (12-0, 5-0) capture the regular-season title and the top seed in the Colonial Athletic Association tournament. The Pride fell to 6-7, 2-3.
No. 4 Notre Dame 10, No. 12 Villanova 7: The Fighting Irish (10-1, 5-0 Big East) used an 8-0 run and tough defense to hold the Wildcats (8-5, 4-1) scoreless for two quarters. Sean Rogers had a hat trick for Notre Dame.
No. 19 Fairfield 9, No. 10 Denver 8, OT: Sam Snow scored 32 seconds into overtime to lift the host Stags (11-3, 4-1 Eastern College Athletic Conference) over the Pioneers (7-5, 3-3).
The victory tied the program record for wins.
Georgetown 10, No. 13 Syracuse 8: Matt Winter made 12 saves, including three in the final minute of play to preserve the win, as the Hoyas (6-6, 2-3 Big East) upset the host Orange (7-6, 3-2).
Georgetown, led by Brian Casey with three goals, used a dominant second half to open a four-goal lead against Syracuse.
No. 4 Florida 8, No. 1 Northwestern 7: Gabi Wiegand scored her second and the game-winning goal unassisted with 5:47 left as the Gators (15-2, 5-0 American Lacrosse Conference) upset the top-ranked host Wildcats (14-1, 4-1).
Wiegand finished with two goals and two assists for Florida, which ended the first half on a 3-0 run to take a 5-2 lead at the break.
No. 6 Notre Dame 7, No. 12 Georgetown 6, 2OT: Lindsay Powell scored the game-winner with 40 seconds left in the second overtime as the Fighting Irish (12-2, 5-2 Big East) beat the Hoyas (8-6, 4-3).
Georgetown trailed 6-5 with 2:54 left when Rosie Corcoran scored the game-tying goal to force overtime.
Princeton 12, No. 7 Dartmouth 9: Cassie Pyle scored four goals for the host Tigers (7-6, 4-2 ), who handed the Big Green (10-3, 5-1) its first Ivy League loss.