The champions broke the league points record last weekend by beating Norrkoping 2-1, but still Anders Torstensson's side refused to take their foot off the gas. Tonight, they were gifted the chance to take the lead 11 minutes in from the penalty spot, and Elliot Stroud duly obliged.
It only took Mjallby and Stroud seven minutes to double their tallies - Ludvig Thorell punched a through ball between the Varnamo defenders, sending the 23-year-old through on goal, and again he made no mistake.
Varnamo's challenge only grew weaker after the break, when Souleymane Coulibaly conceded another penalty and was sent off for a second bookable offence just four minutes in. Stroud stepped up again to complete his hat-trick, sending the goalkeeper the wrong way.
Despite their Allsvenskan domination, MAIF had only notched four in a game once all season, until tonight - amid pinball in the Varnamo box, Herman Johansson took control and laid the ball off to Viktor Gustafsson, who planted the ball in the bottom corner from the edge of the area.
Eight minutes from time, the roles were reversed as a rampant Mjallby made it 5-0 - Gustafsson out-muscled his marker on the right and crossed the ball right on the money for Johansson to head home.
With their biggest win of the season, Mjallby reach 72 points and can reach three quarters of a century when they face Hacken at home on the final day on Sunday. After consecutive losses, Varnamo remain on just 16 points.
Also on Monday night, Degerfors picked up a hugely significant point with a 1-1 at home to second-placed Hammarby that has aided their survival hopes going into the final day.
Shortly before the hour mark, the visitors took an expected lead when Montader Madjed found Adrian Lahdo, whose shot was too powerful for Matvei Igonen, who allowed it to squeeze past him at his near post.
But 10 minutes from time, Degerfors drew themselves level - Daniel Sundgren did well to win the ball back in the Hammarby half, quickly finding Elias Barsoum, who drove forward before guiding the ball into the bottom corner from 20 yards out.
1-1 was how it finished, meaning Degerfors go back above Oster into the Relegation Playoff place. One point is the difference between the two, while Norrkoping sit two points above Degerfors.
That means Degerfors need to win on Sunday's final day against Brommapojkarna and hope Norrkoping lose to Goteborg.