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Welling kept their survival hopes alive on Saturday - despite their 12th red card of the season at Alfreton.
The Wings, who climbed out of the drop zone and above Alfreton on goal difference in midweek, knew victory would guarantee them Vanarama Conference football next season.
But they suffered a major blow in the 15th minute when Harry Osborne was sent-off for handball, as he tried to block a shot on goal, and Dan Bradley tucked away the spot-kick to put Alfreton ahead.
The hosts contnued to have the upper hand but Niall Heaton's shot was saved and Tom Shaw fired over from inside the penalty area.
Welling levelled on the stroke of half-time when on-loan Ross Lafayette collected Jake Gallagher's flick, rounded keeper Thomas Flynn and slotted in.
The Wings replaced forward Kieron St.Aimie with defender Sam Berry at the break and they took the game to their hosts.
Dominic Vose saw his shot from distance turned behind and Sam Corne fired wide before Chris Bush turned the ball in from close range after Berry headed a deep Vose free-kick back across goal to put Welling ahead.
That goal meant Alfreton had to score if they were to avoid being relegated and they duly delivered with around 20 minutes left. John Johnston crossed and substitute Massiah McDonald converted.
Welling keeper Michael McEntegart denied Jimmy Phillips late on while Lafayette's shot was blocked by Flynn at the other end as neither side could find a winner.
The Wings now need to match Alfreton's result on the final day of the season to stay up. Welling host Southport while Alfreton visit title-chasing Bristol Rovers.
Welling: McEntegart, Osborne, Chambers, Bush, Williams, Gallagher, Corne (Fagan 86mins), Vose (Healy 79mins), St.Aimi (Berry 46mins0, Lafayette, Jefford. Subs not used: Henly, Akinde. Attendance: 1,593.