The Big Red offense was led by Steve Mock and Chris Langton with two goals apiece.
Dartmouth (2-5, 0-2 Ivy League) took a 1-0 lead when Brendan Rotanz scored with 5:28 left in the first quarter, but Cornell (7-1, 3-0) went on a 6-0 run that spanned both halves to pull ahead.
No. 4 Massachusetts 15, SAINT Joseph's 3: Will Manny had a hat trick, and the host Minutemen improved to 9-0 for the third time in program history.
No. 6 Denver 15, Hobart 8: The host Pioneers (6-3, 2-1 Eastern College Athletic Conference) went on a 5-0 run in the third quarter to post their second straight victory.
Mark Matthews had a game-high four goals for Denver as the Statesmen fell to 2-6, 0-2.
No. 20 Georgetown 8, Lafayette 5: Zac Guy had two goals and an assist and the visiting Hoyas (5-3) used a 4-0 run in the third quarter to distance themselves from the Leopards (2-7).
No. 1 Northwestern 13, No. 16 Ohio State 12, OT: The host Wildcats (10-0) fell behind, but a four-goal rally late in the second half forced overtime, in which Shannon Smith scored twice for the win at Foxborough, Mass.
The Buckeyes (7-3) led 11-7 when Northwestern went on the 4-0 run.
The Crimson fell to 4-5.
No. 9 Dartmouth 14, Brown 8: Liz Calby scored four goals, including the first of a 4-0 run to open the game, for the visiting Big Green (7-1, 3-0 Ivy League). The Bears fell to 5-4, 1-2.
No. 11 Virginia 12, Boston College 10: Katie Slater and Ainsley Baker each had a hat trick and the host Cavaliers (8-4, 2-2) rallied in the second half to win.