Argentina coach Marcelo Loffreda has launched a withering attack on referee Chris White following his side's 27-20 defeat to Wales in Cardiff.
Loffreda will join Premiership giants Leicester after the World Cup
Loffreda accused White of "coaching" the home side and claimed he applied different rules to each team.
He added that the World Cup, which starts next month, could have a "lot of trouble" if major sides got favourable treatment in France.
"I am worried about what will happen in the World Cup," he said.
"If there is one rule for one team and another for the other team in the same game, we will have problems, we will have a lot of trouble.
"I am really aware of what will happen at the World Cup. If this continues in the same way we will have to make a formal statement because we are playing with another set of rules."
Loffreda, who takes over at Premiership giants Leicester after the World Cup, was annoyed that the Pumas did not get a penalty try late on when they laid siege to the Wales line.
He was coaching not refereeing
Argentina coach Marcelo Loffreda on referee Chris White
"I'm not arguing about the result of this game. Wales deserved to win, no problem about that," said Loffreda.
"But I am a bit confused, I don't understand what happens with the interpretation of the rules because in some parts of the game there was a rule for Wales and there was another rule for Argentina.
"Many things were awarded to Wales which were not awarded to us or were awarded for us and wasn't awarded for them.
"Chris White only saw one team. He only penalised one team. When we played against Ireland in Santa Fe two months ago the referee awarded a penalty try to Ireland when we collapsed the maul once, only once.
"Today there were clearly three times when Wales collapsed the maul. That's a penalty try.
"He was still coaching the team. He was not refereeing a team, he was coaching a team.
"He said, maybe 45 or 50 times, 'Reds, hands away'. He was coaching not refereeing. He insisted many times that Wales open the gap at the line-out and he never gave us a free-kick."
Loffreda was also angry when White went to the television match official (TMO) when substitute Martin Durand thought he had scored in the dying seconds.
The TMO ruled that Durand had knocked on and Argentina were denied the chance to level the score.
"Chris White said to the TMO at the end 'give me a reason why I cannot award the try'," said Loffreda.
"That was a try, why is he asking the TMO? If he didn't want to give a penalty try, give a try."