Rotherham United guaranteed their Championship status for another season with a 2-1 win over Reading, consigning Millwall and Wigan Athletic to relegation in the process.
Steve Evans' Rotherham, promoted via the League One play-offs last term, would have been safe already but for a three-point deduction for fielding an ineligible player in a fixture against Brighton and Hove Albion earlier this month.
But Millwall and Wigan's reprieve proved brief as Rotherham grabbed the initiative after the break following a goalless first half at the New York Stadium.
Matt Derbyshire opened the scoring in the 52nd minute when he turned home Danny Ward's cross from the left at the near post and the same man provided the assist for Lee Frecklington to stab home from close range six minutes later.
The quickfire double raised the noise levels around the ground, but Oliver Norwood's long-range goal in the 87th minute set up a nervy ending that Rotherham managed to withstand as fans flooded onto the pitch in celebration.
In League One, Colchester United failed to climb out of the drop zone after being held 1-1 at home by fourth-placed Swindon Town.
Jacob Murphy side-footed Colchester into a first-minute lead, but Ben Gladwin headed home a second-half corner to earn a share of the spoils.
Colchester are now one point shy of safety and face a Preston North End side who need to win to ensure promotion at the Weston Homes Community Stadium on Sunday.