The Bearcats beat the Mariners, 6-5, in Maritime Junior Hockey action in front of 1,501 spectators.
Alex Hazelhurst was the only Truro member to score during the first period, to bring the Bearcats within one goal of the Mariners.
With three goals from the Bearcats in the second - from Kyle Morrison, Dylan McGuigan and Daniel Perigo - and only one coming from Yarmouth, Truro took the lead by one.
Both teams scored two goals in the final period, with Truro's coming from Grant West and Philip Fife.
Shayne Campbell picked up the win for the Bearcats, stopping 36 shots, while Travis Wilkins stopped 31 in the loss.
Truro's next game is on the road on Thursday against the Weeks Crushers.