Any optimism was crushed by the medical professional, who insisted that the Brazil superstar would not be able to feature in the final should the Selecao beat Germany on Tuesday
The striker injured a vertebra in his back after a challenge from Colombia's Camilo Zuniga in the quarter-finals, that ruled him out of the rest of the tournament.
However, there have been increasing murmurings in Brazil's media that the Barcelona forward, 22, could pull off a remarkable turnaround to feature at the Maracana should the Selecao see off Germany in their semi-final on Tuesday.
Reports had even surfaced that the forward himself believes he can recover in time as the initial, excruciating pain of the injury has faded.
Runco, though, moved to clarify the situation by confirming that there is no way the striker would be able to feature as it could risk ruining his future fitness if the current injury is aggravated.
"There's no chance of him playing in the final of the World Cup," the Brazil team doctor told TV Globo. "He can be with the team, yes, but there's no chance he can be on the field. No way.
"We will not create the illusion of something that does not exist. We have no choice but to not play him.
"Neymar has an injury which needs to heal. It could seriously risk his recovery if he plays, and jeopardise his career."
Brazil will also be also without suspended captain Thiago Silva for the clash with Germany for a spot in the World Cup final where fellow semi-finalists Netherlands or Argentina await.