Connor Rankin scored twice and the Tri-City Americans went on a three-goal tear midway through the first period to take control of Monday's 6-3 win at Prince George.
The two teams will take to the same ice today to complete the two-game set in British Columbia.
Justin Feser and Mitch Topping scored alongside Rankin as the Ams stormed back after giving up an early power-play goal. Feser also had an assist to hit the 100-point mark.
After the Cougars pulled within a goal late in the first, Lucas Nickles and Rankin scored about a minute and a half apart in the second. Beau McCue capped Tri-Cities' scoring nearly 8 minutes into the third period.
While Prince George remained eight points behind Seattle for the WHL Western Conference's eighth and final playoff berth, the Americans (39-23-1-2) pulled one point ahead of Spokane into fourth place with less than two weeks left.