Max Novak scored midway through the third period to snap a 2-2 tie, and Union overcame some discipline issues to beat Dartmouth, 4-2, and advance to the ECAC Hockey tournament semifinals Friday in Lake Placid.
The top-seeded Dutchmen won the best-of-three quarterfinal series, 2-0. They will face either Cornell or Clarkson at 4 p.m. at Herb Brooks Arena. Clarkson beat Cornell, 4-1, to even that series at a game apiece.
Union gave Dartmouth seven power plays. The Big Green scored on two of them in the first period.