Lionel Messi was involved in furious confrontations as Manchester City crushed Barcelona in the Champions League.
The five-times FIFA World Player of the Year launched an angry half-time tirade at Hungarian referee Viktor Kassai, who failed to award him a first half penalty.
Superstar Messi confronted the referee as the players left the pitch at the interval and continued his rant as they headed down the tunnel.
Witnesses were shocked at his behaviour as the forward lost the plot after claiming he was brought down by City midfielder Fernandinho.
Barca substitute Arda Turan is also believed to have confronted the referee about the decision in the tunnel following the final whistle.
After the match, City striker Aguero, who is close friends with fellow countryman, admitted the Nou Camp darling was fuming.
He said: “Whenever you lose you’re not very happy. I saw him there, he was feeling bad. I know him well enough to know when he’s bad, when he’s good. But when you lose, nobody’s good.”
Although City deny any altercation, Aguero added: “I thought Messi said something to me but he didn’t, and then we talked about other stuff. It was nothing serious. I heard something but I don’t know what happened.
“When someone loses, you have to respect them. Leo wasn’t in the mood to talk and I respect that.”
Messi was unhappy with Fernandinho for his first half challenge, but the Brazilian midfielder put out an Instagram post saying reports of a row after the match were “absurd untruths”.