A sold-out crowd watched the Eagles defend home ice in Sydney.
Cape Breton nabbed a crucial 2-1 victory against the Drakkar.
Nicolas Ruccia stopped 39 of 40 shots in the win, while Charles-Édward Gravel stopped 24 of 26 shots in the loss.
Baie-Comeau leads the QMJHL playoff series 2-1.
The Eagles will look to tie the series Tuesday in game four at Centre 200 – which is also a sell-out.
Puck drops at 7 p.m.