Walsall stunned Peterborough 3-0 to take their relegation battle to the final day and deal a massive blow to Posh's play-off hopes.
Strikes from Andy Cook and Josh Gordon, plus a Daniel Lafferty own goal, gave the struggling Saddlers a first win in nine games.
Walsall goalkeeper Chris Dunn made a fine save to thwart Marcus Maddison's early 25-yarder for Posh before Gordon steered Luke Leahy's low cross just wide from 12 yards for the Saddlers.
The hosts went ahead in first-half stoppage time as Cook headed home Scott Laird's deep cross from close range.
Walsall doubled their lead on 57 minutes as Lafferty turned Gordon's vicious low cross into his own net and they sealed the points on 74 minutes as Gordon stabbed home Cook's near-post ball.
Ivan Toney fired a 20-yard free-kick inches wide late on for below-par Posh, who slip four points behind sixth-placed Doncaster albeit with a game in hand.
Walsall rise to 22nd but must win at Shrewsbury and hope other results go their way to survive.