Steve King found his own net to give Welling a 28th-minute lead but the Conference South club’s player-manager Jamie Day was sent off shortly afterwards.
It took until the 73rd minute for the Beachboys to take advantage of their extra man, and after the equaliser from Tony Stokes they were level for only three minutes before Joe Healy won it from the spot and earned Welling a home tie against Thurrock.
Waltham Forest improved their position in Ryman North with a convincing 3-0 home win over Harlow, who might have fared better had a fierce free-kick from Joe O’Donoghue not crashed against the Forest bar early in the game.
Forest took the lead shortly afterwards, in the 13th minute, when a corner was headed back across goal by Tom Vickers for Manu Dagher to finish.
They might have gone further ahead before the interval, but Dmitri Larin’s header bounced on the bar and Vickers’ drive struck a post.
They increased their lead in the 73rd minute when Corey Whitely fired the ball across from the right flank and a late swerve goalwards caught out giant Harlow keeper Bertrand Bossu.
Adrian Clifton wrapped it up ten minutes later when he was allowed to turn and shoot home from ten yards despite being surrounded by five defenders.
Eastbourne moved into the top half of the Ryman South table with a 3-2 home victory over Merstham, who recovered from Sonny Cobb’s 18th-minute opener for the hosts and drew level through Fabio Saraiva in first-half injury time.
Dean Gunner fired Merstham into the lead 11 minutes after the restart but it was in vain as Ben Austin made it 2-2 seven minutes later and Matt Geard won it for the home side with nine minutes left.
Keep up-to-date with our exclusive email newsletters.
Subscribe