Eric Kroshus broke a third-period tie with a power-play goal, and Harvard beat Princeton 4-3 on Saturday.
Patrick McNally, Marshall Everson and Danny Biega added goals for the Crimson (4-3-3, 3-3-2 ECAC Hockey), who got 31 saves from Steve Michalek.
Marc Hagel scored twice and Kevin Mills added a goal for the Tigers (4-8-2, 3-6-1).