Having played out a stalemate with Malmo last time out, AIK looked set for a second goalless draw in succession, this time against newly-promoted Oster, but Bersant Celina had other ideas.
With 10 minutes left, a half-clearance fell to him on the edge of the area, and he produced a beautiful first-time strike which flew into the top corner.
As well as the goal, the 1-0 victory will be remembered for an unusual yellow card shown to the visitors' kit-man, Hakan Sjoberg, who was attempting to replace towels along the touchline that kept disappearing in the first half.
Arguments between Sjoberg and the Oster staff ensued, with the home manager Martin Foyston saying after the game, "I don't think we should allow them to hang their laundry in our home arena."
Despite the odd scenes, AIK are the first team to reach double figures in terms of points, while Oster have won one and lost three of their opening four.
Relinquishing first place are Hammarby, whose three-match winning run to begin the campaign was ended abruptly by Mjallby, who move third with a 3-1 home win.
The visitors' defence was breached for the first time all season when Mjallby broke the deadlock after seven minutes - Abdullah Iqbal dug out a cross and Herman Johansson arrived at the back post to prod it home.
The Bajen passed the first test of their comeback abilities, drawing level 10 minutes later, when pinball in the Mjallby box concluded with Montader Madjed hammering the ball in off the crossbar.
But the Hallevik side were not done there - after 33 minutes, Johansson turned provider, laying the ball off to Nicklas Rojkjaer, who steered it into the bottom corner.
The one-goal lead became two in first-half stoppage time, when Jacob Bergstrom's cutback allowed Ludwig Thorell to poke the ball in at the near post.
Two draws followed by two wins make Mjallby one of just three sides left unbeaten in the division, one point shy of Hammarby.
Along with Mjallby and AIK, Malmo are the other side yet to taste defeat in 2025, not that a 1-1 home draw against Sirius left a sweet taste in the mouth.
The Eleda Stadion was silenced after 10 minutes, when Saba Mamatsashvili swung in a corner which missed everyone in either sky blue or black & blue, and nestled in at the far post.
Malmo dominated the possession, shots and shots on target throughout the rest of the match, but needed the awarding of a penalty for handball with five minutes left to save themselves and deny Sirius a huge win.
Lasser Berg Johnsen held his nerve to beat Ismael Diawara from 12 yards, but that didn't stop Malmo slipping to fourth, as the Blasvart pick up their first point since matchday one.
Home hearts were broken in the 97th minute in the Gothenburg derby at Gamla Ullevi, as Hacken earned local bragging rights with a 3-2 win over Goteborg.
Midway through the first half, Srdjan Hrstic was at full stretch to turn home a low cross and give Hacken the lead, but IFK turned things around. Kolbeinn Thordarson's header from a corner squirmed through a crowd to equalise, before Max Fenger dispatched a penalty in the 45th minute.
However, that was not enough for the hosts to lead at the break, as Hacken hit back in stoppage time through Amor Layouni's cool header.
That was how it stayed until deep into second half added time, when Goteborg were caught out by a simple free-kick routine, and Simon Gustafson kept his composure to win the match.
That ends a two-match winning run for IFK, as Hacken join them on six points.
In fact, five sides find themselves on six points, including Norrkoping who, despite as many losses as victories, are the highest scorers in the Allsvenskan so far, putting three unanswered strikes past Halmstad at home to reach 10 for the season.
Isak Sigurgeirsson and Christoffer Nyman scored within three minutes of each other, before Ismet Lushaku added a third in injury time. Halmstad, in the bottom two, have now conceded nine, the joint-most alongside - coincidentally - Norrkoping.
Joining the six-point clan are Brommapojkarna who registered a 3-2 win over Varnamo, who remain the only side yet to pick up either a win or a point.
The visitors came close to getting off the mark, coming from 2-0 down as second-half goals from Frank Junior Adjei and Simon Thern cancelled out Alex Timossi's and Ezequiel Alladoh's strikes either side of the break.
But the Boys from Bromma settled matters in the 91st minute, when Kaare Barslund fought hardest to get on the end of a cross.
A penalty, dispatched by Simon Hedlund - was required for Elfsborg to beat Degerfors 1-0 away from home and record back-to-back wins after a tough beginning to the campaign.
The round concluded on Monday night, as Djurgarden's European exploits continued to disrupt their domestic form, as they drew 0-0 at home to GAIS, leaving them on four points so far, one fewer than the visitors.
