Paraguay coach Ramon Diaz said he and close friend Dunga will not be on speaking terms when their respective sides face off in the Copa America quarter-finals on Saturday.
Diaz and Brazil coach Dunga both featured in Italy's Serie A in the late 1980s and also crossed paths in Japan in 1995, maintaining the relationship they developed as contemporaries in their playing days.
On Saturday, however, they will be trying to beat one another.
"It's not a friendship from now, but from a long time ago," Diaz said on Friday in Paraguay's pre-match news conference.
"We have been out to eat together a lot of times and we have a great relationship.
"Dunga is a great coach and I congratulate him because he has changed Brazil a lot.
"They will be a tough and difficult rival.
"But friendship doesn't count here."
Diaz has enjoyed plenty of success himself as coach of River Plate in the past, but claims Saturday's showdown represents the most significant match of his career.
"It's the most important one," he said.
"To be representing an entire country and what that means, the future of these players. We are going to give everything we can to try to make it through.
"We want to advance, and this is a final for us."
Paraguay remain unbeaten in the Copa after a 2-2 draw with Argentina, a 1-0 win over Jamaica and a 1-1 stalemate with Uruguay in Group B.
"We are in our best moment," said Diaz, who confirmed striker Roque Santa Cruz will start after being used off the bench in their clash with Uruguay.
"It will be a hard, intense game, but we are confident we will play a great match.
"We have had a relaxed week to work on everything: the mental aspect, tactics, dead balls... We are very well prepared."
Brazil lost Barcelona forward Neymar to a four-match ban during the tournament, and Diaz said the absence was telling for the spectacle.
"They are a great team with great players, but it's a shame Neymar is not here," Diaz said.
"The spectacle loses out when players like him are missing."
Paraguay upset Brazil in a penalty shoot-out at this stage of the competition four years ago, with goalkeeper Justo Villar the hero that day as he saved a spot kick from Thiago Silva to see them advance to the last four.
"That's history now," said Villar, now 37.
"Although it was the same phase of a continental competition, every game begins to write itself when it starts.
"But I have great memories - and I would love to repeat it."
