Racing Club have criticised Atletico Madrid for allegedly giving sought-after striker Lautaro Martinez a medical examination without their permission.
Martinez, 20, is regarded as one of South America's most talented players under the age of 21, establishing himself in Racing's first team and Argentina's youth setup.
The striker has been heavily linked with a move to Atletico, a club Racing have strong ties with due to Diego Simeone's time as a player and coach with the Avellaneda-based side.
Atletico have already had one bid of EUR12.75million rejected by Racing, but that did not stop the Spanish side from examining the youngster, according to club president Victor Blanco.
"Lautaro came from an operation on his foot and what they [Atletico] did was an X-ray or examination of how he had been in the operation," Blanco said.
"It was nothing more than that, but it was not good to do it either.
"It was bad for the people of Atletico to do it, because he should have at least asked us for permission, which we would have given him."
Blanco is confident that he will be able to keep hold of Martinez for the time being, however, believing that the youngster - who rejected a move to Real Madrid as a teenager - is eager to play in the 2018 Copa Libertadores with Racing.
"I have talked with the player and we are all thinking about the future," said Blanco. "I am 90 per cent sure that Lautaro will ask to play [in the Copa Libertadores], because he could go now, but he has the dream of winning the Copa Libertadores with Racing.
"If they [Atletico] don't reach the price and the conditions that Racing wants, which is for him to stay and play the Copa Libertadores, then he will not be sold."