Port Vale’s relegation to Sky Bet League Two was confirmed with a 1-0 defeat at promoted Cardiff.
Vale boss Jon Brady said his side would not give up the fight after last weekend’s goalless draw against Wigan.
But Rubin Colwill’s eighth goal of the campaign finally broke the deadlock at Cardiff City Stadium in the 79th minute and sent Vale down.
Port Vale headed to the Welsh capital to face a Bluebirds team which had clinched promotion back to the Championship with a 3-1 triumph at Reading four days earlier, knowing they had to win all of their four remaining fixtures and hope Leyton Orient and AFC Wimbledon failed to pick up any points to survive.
There was little or no meaningful action in the opening 45 minutes, Joel Colwill forcing Joe Gauci into the only save of the half in the Vale goal.
The home side needed a brilliant save from Nathan Trott three minutes after the restart to keep out a Ben Garrity header from a corner.
Yousef Salech and Joel Colwill had two bites of the cherry in front of goal just past the hour mark before Chris Willock curled a cross to the far post for Rubin Colwill to head home.
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