The last-gasp hammer-blow cancelled out Liam Lawrence's first-half strike as City succumbed to a stoppage-time equaliser for the second game in succession.
And those last-minute jitters have proved costly, as two draws on the bounce have seen the Potters plunge to eighth when maximum points would have consolidated a top-six spot.
A nervy first half hardly captivated the imagination, but nevertheless both sets of supporters would be justifiably bewildered at how only a solitary goal separated the sides at the break.
Despite the glaring absence of any measured football, each side managed to waste golden opportunities early on - Dean Windass should have snatched the lead for the Tigers. The evergreen striker stole a yard on his marker before angling Nicky Forster's low centre into the travelling contingent behind Steve Simonsen's goal.
Danny Higginbotham would have made it onto the score-sheet were it not for the reflexes of Boaz Myhill greeting the defender's uncontested header in the visitors goalmouth.
Andy Griffin blasted over late in the first half before the deadlock was finally broken when Lawrence jinked his way into enemy territory. The fleet-footed winger skipped into the box before watching his tame effort take a fortuitous deflection off Andy Dawson which looped over the stranded Tigers keeper.
Parity seemed to be restored after the restart when Windass charged down an idle back-pass from Griffin only to see his finish rebuffed by referee Andy D'Urso who saw an infringement in the challenge.
But it was City that took the initiative as chances fell thick and fast at the feet of the Hull players, but each was met with a wasteful boot, Lee Hendrie the most culpable party. The City schemer latched onto Ricardo Fuller's rapid breakaway but, with the goal at his mercy, he dragged his shot wide when really City should have been celebrating their second goal.
And the hosts were left kicking themselves for not killing it off when Barmby rammed his volley over Simonsen to lift the Tigers a point away from the Championship trapdoor.