Malmo and Vaxjo had successfully navigated the Eighth-finals in the past week, but taking on the number one and two ranked sides was going to be a step up.
So it proved, as regular season winners Brynas shrugged off the poor form they showed in their recent fixtures to run out 5-1 winners against Malmo on home ice.
Anton Rodin broke the deadlock after seven minutes, which is how it stayed until the end of the first period, before Jordan Schroeder settled some nerves inside the Monitor ERP Arena, doubling the lead just 32 seconds after the restart
A hooking call against Rodin allowed Malmo to get back into the game with a powerplay goal from Lassi Thomson with seven minutes of the middle period to play.
However, Johannes Kinnvall restored the two-goal cushion at 18:23 in the second, before the third period belonged to Brynas - Jakob Silfverberg added the fourth before Tyler Vesel scored into an empty net late on.
Gavle will play host again for game two of the best-of-seven series on Saturday.
Second seeds Lulea also registered a four-goal victory to open their postseason schedule, winning 4-0 at home to Vaxjo.
After a scoreless first period, The visitors resilience collapsed three minutes into the second when Albin Lundin put Lulea ahead, and their night got worse when Eric Martinsson was ejected for butt-ending after 40 minutes of play.
Lulea used the substantial powerplay at the beginning of the third period to put the game to bed, as first Pontus Andreasson, then Brendan Shinnimin put the home side 3-0 up.
The fourth was scored into an empty net by Eetu Koivistoinen in the final three minutes.
Game two of this series will also be played on Saturday, while the other two Quarter-finals - Farjestad vs Skelleftea and Frolunda vs Timra - get underway tomorrow.