Manchester's Jeff Giuliano scored at 1:46 of the second overtime Friday night, giving the Monarchs a 6-5 win over the visiting Hartford Wolf Pack.
It was the first overtime goal in the Monarchs' postseason history (1-4).
The Monarchs now lead the AHL Atlantic Division semifinal series 2-1. The series resumes with Game 4 in Manchester on Sunday afternoon.
Giuliano's goal was his second of the game, and it spoiled a dramatic Wolf Pack comeback that saw Hartford overcome a 5-2 third-period deficit, capped off by Brad Smyth's game-tying goal with 59 seconds remaining in regulation.
Noah Clarke also shad two goals for Manchester, while former Ranger Alexandre Daigle had four assists, and Tim Jackman added three for the Monarchs. Goaltender Barry Brust was the Manchester hero with 45 saves, including 16 in overtime.
Dwight Helminen had a goal and two assists, and Chad Wiseman had three assists for the Wolf Pack, who raced out to a 2-0 lead before giving up five straight Manchester goals.