The two sides who recorded the biggest victories in round one met in Uppsala in round two, but with Hammarby's win coming against champions Mjallby, it was seen by many as the more impressive.
But that performance counted for nothing tonight, as Sirius took the lead in just the ninth minute when Isak Bjerkabo picked up the ball just inside the Bajen half, was afforded space to play a one-two with Oscar Krusnell and steered the ball into the bottom corner from the edge of the area.
The visitors completely dominated the ball, but failed to create clear-cut opportunities to get back in the game, which Sirius sealed with 20 minutes still to play.
A clearance downfield from goalkeeper David Celic was contested in midfield by Robbie Ure and Hammarby's last defender Victor Eriksson, and when the Scottish strike won the battle, he raced away and clipped his second of the season past Warner Hahn.
Two wins and two clean sheets sees Sirius lead the table, ahead of Djurgarden, the only other side to be on maximum points after two rounds.
A 95th-minute leveller ensured Brommapojkarna earned a second successive 2-2 draw to begin their 2026 campaign, while AIK have taken four points from their first two league games under Jose Riveiro.
The match came to life just before the hour mark, when BP goalkeeper Leo Cavallius passed the ball straight to Taha Ayari at the edge of the box, before Zadok Yohanna took over by squaring to Bersant Celina, who guided the ball past Cavallius.
But the home side were level within three minutes, as a deep cross from the right was headed against the post by David Isso, and Mads Hansen was quickest to the rebound and tucked it away.
Gnaget looked to have done enough for another win when Victor Andersson leapt high to head home a Johan Hove cross with 12 minutes of the 90 remaining, only to be denied five minutes into added time.
A long, searching pass caused havoc in the AIK penalty area, and a fortunate ricochet saw the ball sit kindly for Alex Timossi, whose shot was deflected past Sweden's number one, Kristoffer Nordfeldt, to share the spoils.