Neymar's father expects his son to miss "between six to eight weeks" and ruled out any chance of playing against Real Madrid next week, he told ESPN Brasil on Tuesday night.
The Brazilian star suffered a crack in the fifth metatarsal of his right foot and sprained his ankle during Paris Saint-Germain's 3-0 win over Marseille on Sunday, but coach Unai Emery insisted earlier on Tuesday that no decision has been made over whether Neymar will have surgery.
However, Neymar Sr, who serves as his son's agent and manager, told ESPN that a quick return is out of the question, despite PSG's hopes that their star player will recover in time for next week's crucial Champions League clash against Real Madrid.
"PSG already know they will not have Neymar in the next few games, six weeks minimum, because this treatment will last six to eight weeks," Neymar Sr said. "That is already certain, regardless of surgery. What we can't do is something that may cause a fracture in the future."
He added: "Yes, of course he is out against Real Madrid. It is absurd if anybody thinks otherwise."
Neymar Sr also said that PSG and his son are both waiting for Brazil's medical staff to arrive to decide about whether to have surgery, but he was positive that the injury was of the kind that would call for an operation.
"We are waiting on PSG to settle this, where [surgery] will happen, it is not up to Neymar to decide," Neymar Sr said. "It is not my decision, or his. I'm not a doctor, our family doesn't have any doctors.
"We have to wait on the club's decision, which they are waiting the right time to make, they are waiting the Brazilian national team doctor to arrive. Neymar will not decide this."
The doctor for Brazil's national teams, Rodrigo Lasmar, confirmed earlier on Tuesday that he was en route to Paris.
National teams coordinator Edu Gaspar told AS earlier that there was no conflict between the Brazil federation and PSG over Neymar's treatment, saying: "We always uphold the decisions made by the clubs."
Earlier, sources close to both the player and PSG told ESPN FC's Jonathan Johnson that Neymar does not want to play with painkillers if that is the only way to take the pitch, because he feels the method would increase the risk of the injury becoming more serious than it already is.
Neymar is desperate to play against Madrid if at all possible, the sources added, but he understands that he might not be able to do so and he is not prepared to risk the rest of the season with PSG and the World Cup with Brazil in order to play with the aid of injections next week.
The sources also said that those closest to Neymar are keen for him to undergo surgery as soon as possible, if it is ultimately unavoidable, to ensure that he does not jeopardise his World Cup, which begins for Brazil on June 17.
PSG, though, want to wait and see if reduced swelling makes surgery avoidable, which is why Emery called for calm during his news conference.
"No decision to operate has been taken," Emery said, rejecting earlier reports that Neymar would need three months to recover. "I have met with the doctor, and he told me that the sprain was swollen. His fifth metatarsal has a crack in it. We will take a decision in the coming days. However, for the moment, calm is needed."
With PSG already trailing Real Madrid 3-1 after the first leg, Neymar's absence next week would be a huge blow -- particularly when considering they spent €222 million to acquire him last summer in large part to improve their Champions League record.
The French club crashed out in the quarterfinals in four straight seasons before falling to Neymar and Barcelona in the round of 16 a year ago.