Almiron, who helped Atlanta United win MLS Cup at the same stadium in 2018, found the bottom corner of the net with a left-footed finish to pull Newcastle level deep into first-half stoppage time.
Joshua Kimmich's powerful 63rd-minute header from Raphael Guerreiro's cross was enough to send the Germans through to the semi-finals 3-2 on aggregate after the two teams had drawn 2-2 in London in the first leg.
With fit-again Michael Olise subbed on in the second half for his first appearance of theseason and Eze electric, the momentum seemed to be firmly with the home side.