Russia came from two sets down and saved seven match points before beating Brazil to secure a place in the final of the women's volleyball tournament.
Russia looked to be heading for defeat when facing five match points at 19-24 in the fourth set, but they fought back and eventually took the set 28-26.
Inspired by the towering Ekaterina Gamova, they went on to seal a stunning 18-25 21-25 25-22 28-26 16-14 victory.
They will face China on Saturday after they beat Cuba in five sets.
"I have been coaching these girls before they turned 14 and my main point of coaching them was to develop their character," said veteran Russian coach Nikolay Karpol.
"I think it was nerves because we were so close to winning. It was just a matter of one point and we just couldn't take the
stress," Brazilian blocker Walewska Oliveira said.
China feared they could have followed Brazil after losing a two-set lead when Cuba pulled their semi-final back to 2-2.
But China held their nerve to come out 25-22 25-20 17-25 23-25 15-10 winners.