The singer tripped up and suffered a nasty injury during the group's show at The Forum venue in Copenhagen.
A gig-goer tells Wenn, "Paul fell over and cut his arm... I think his boot got stuck and he fell over himself... We saw him bleed and then shrug it off... When he was down he was continuing to play... flat on his back."
Stanley's mishap was not the only problem during the show, as the band's huge mechanical spider-shaped stage set is also said to have broken down.
The concert-goer adds, "Halfway through the gig it was announced that the spider was dead... But there was new awesome pyro (pyrotechnics) which went down well."