The only goal of the game arrived with six minutes left in the first period, when the home defence afforded Marcus Karlberg time to pick his spot and fire past Erik Kallgren.
Brynas recorded 29 shots on goal during the match, but could not find a way past Marcus Gidlof, who registered an impressive shutout.
Despite the slip-up, Brynas' lead at the top is still a healthy 10 points with only six rounds remaining in the regular season, after second-placed Frolunda failed to close the gap.
The Gothenburg side suffered a 5-2 defeat on the road to Timra, who sit top of the form table with four wins in their last five.
Filip Hallander and Jonathan Dahlen both scored for the third match running to give Timra a 2-0 lead within the first eight minutes.
Though Filip Hasa reduced the deficit, goals either side of the break between the first two periods from Oliver Kapanen and Anton Lander all but sealed the win after 21 minutes of play.
Erik Thorell gave his side hope midway through the second period, but with a little over two minutes left in the third, Erik Walli-Walterholm completed a comfortable win for Olli Jokinen's men.
Farjestad have gone third in the standings with a 5-3 win on the road at Malmo Redhawks - a second win in succession after a poor run of six losses in a row, including in the Champions Hockey League final last week.
They have gone ahead of Lulea in the table on goal difference, thanks to three unanswered goals in the third period giving Skelleftea a 3-1 win away from home.
That gives Skelleftea a two-point cushion ahead of the chasing pack in the race for the top six, as Vaxjo needed overtime to defeat Linkoping.
Rogle's 4-1 win over bottom side HV 71 leaves themselves, Vaxjo and Leksand on 68 points apiece in what is sure to be a dramatic race for the quarter-final places.
Malmo, meanwhile, remain in the all-important 10th place, but are now only three points clear of Orebro after they picked up a 3-1 win against Modo.
