With first place and local bragging rights at stake, the atmosphere was fervent at Strawberry Arena as Hammarby made the short trip to AIK.
There was plenty of endevour from both sides, with a total of 24 shots across the 90 minutes. Bersant Celina was creating some of the better AIK chances in the first half, while Victor Andersson struck the post midway through the second.
Abdelrahman Boudah and Paulos Abraham had some of the better efforts from the visitors, but neither side could find the killer goal and, as a result, AIK recorded a second draw in a row to move onto 22 points and remain unbeaten, while Hammarby remain a point further back.
After the Sunday stalemate, Mjallby knew they would return to first place in the standings with a win over Brommapojkarna on Monday night.
Midway through the first half, they were well on their way to the top, as Nicklas Rojkjaer found Abdoulie Manneh at the edge of the penalty area, and the Gambian buried his strike into the bottom corner for his sixth goal of the season.
After dominating the first half, Mjallby found themselves hanging on in the latter stages as the Bromma Boys came close to an equaliser, but the Hallevik natives held on for all three points, taking them one clear at the top.
Mjallby's closest challengers are Elfsborg, who also jumped above AIK and Hammarby on Monday night thanks to a 4-0 victory over Djurgarden, taking second place on goal difference.
It took Elfsborg less than nine minutes to get the home crowd on their feet when a long-range drive from Ihler was too powerful for the despairing dive of Filip Manojlovic.
Ihler added his second shortly before the break - he ran onto a Leo Ostman flick on and beat the offside trap before finishing well.
Besfort Zeneli rounded off a fine move with a lovely curling finish into the bottom corner for 3-0, before Ihler completed his hattrick on the hour mark - Niklas Hult picked up his second assist in four minutes by working his way into the area and squaring to the Dane, who tapped home his sixth of the campaign.
Daniel Stensson saw red late on for stamping, compounding an awful evening for Djurgarden, who sit 11th after back-to-back defeats.
Malmo are still at the head of the chasing pack, sitting fifth but now only five points off the top thanks to a comfortable 3-0 win at home to Halmstad.
An Anders Christiansen opener followed by an unfortunate own goal from Aleksander Damnjanovic put the champions in control at half-time, before Isaac Kiese wrapped up the points just after the hour mark. Successive losses for Halmstad see them stay 13th, as Malmo go three games unbeaten.
A second brace in as many matches for Samuel Leach saw Hacken climb to sixth and end bottom side Varnamo's two-match unbeaten run with a 2-0 result, while a brace of his own for Sebastian Jorgensen help Norrkoping return to winning ways by beating Sirius 2-1 on the road.
Also at the double was Goteborg's Tobias Heintz, who struck twice away at Degerfors inside an opening 32 minutes in which Max Fenger also got on the scoresheet for the rampant visitors. The home side pulled one back in the second half through Marcus Rafferty, but they couldn't stop IFK running out 3-1 winners.
That win takes Goteborg above their city rivals GAIS, who were held to a 1-1 draw with Oster, who took the lead through Alibek Aliev before a fourth in two games for Ibrahim Diabate drew GAIS level.