Backing up a 5-2 win in Gavle with a dominant 5-1 display in their first Finals match on home ice, Lulea were favourites to open up a two-match lead in the second meeting at Coop Norrbotten Arena.
Brynas, though, had not read the script - they took the lead in the ninth minute through Jack Kopacka's first goal of the series.
The hostile atmosphere was not having its desired effect on the visitors, and less than four minutes later, Jordan Schroeder scored unassisted on a powerplay after Marcus Hardegard was sent to the box for tripping.
The home crowd were left stunned in the 14th minute, as the Gavle side took a 3-0 lead when Axel Andersson set up Oskar Lindblom.
Lulea did at least get on the scoreboard before the first period was out, as Isak Hedqvist pulled a goal back.
That goal gave the 1996 champions the launchpad they desired to come back into the game - and they reduced the deficit to just one goal when Hedqvist grabbed his second of the night.
In the fifth minute of the third period, the comeback was complete, as Mathias Brome and Linus Omark combined in the build-up and Eetu Koivistoinen was on hand to level the scores.
But less than two minutes after celebrating the leveller, Lulea were behind again thanks to Jakob Silfverberg's second goal in as many matches.
Conceding penalties late on did not help Lulea's cause as they pulled the goaltender, as Brynas capitalised through Bobby Trivigno, who found the empty net to secure the 5-3 win.
The teams head back to Gavle for game five on Monday night.