Emil Riis netted a 95th minute equaliser for the Lilywhites, time almost up when he fired home Jordan Storey' s cross.
Daniel Johnson had scored in the first half, the PNE skipper levelling the game up after Morgan Gibbs-White's early opener.
The Blades regained the lead in the 84th minute through Sander Berge before Riis' late intervention earned the visitors a point.
Here are the PNE player ratings from the clash.
The Blades regained the lead in the 84th minute through Sander Berge before Riis' late intervention earned the visitors a point.
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