Mourinho had criticised Guardiola at an earlier news conference on Tuesday for comments attributed to the Barca coach about a refereeing decision in last week's King's Cup Final when a Pedro effort for his team was ruled out for offside.
Guardiola responded by telling reporters he had been misinterpreted and he was not going to be drawn into what he called Mourinho's game of "constant insinuation".
His colourful language drew murmurs from the stunned journalists as he laid into the Portuguese, who was an assistant Barca coach when Guardiola was a player there in the 1990s, in an uncharacteristically emotional outburst.
"Because Mr Mourinho used my name directly I will do the same," he said.
"We worked together for four years. He knows me and I know him and that's what I will remember and focus on.
"It leaves a bad taste when someone you have worked with believes what he reads rather than you.
"If you think I complain about referees then great, there is nothing I can do."
Mourinho knocked Barca out of last season's Champions League when he was coach of eventual winners Inter Milan and his wild celebrations after the second leg at the Nou Camp, when he charged across the pitch to salute the travelling support, incensed the home players and fans.
His first match against Barca as Real coach in November ended in a 5-0 thrashing for the Madrid club but he has since regained the upper hand with a dramatic King's Cup final win over Guardiola's side last week.
The Barca coach said he and his players would do their talking on the pitch on Wednesday.
"Tomorrow at 8.45 pm we will meet on the pitch - away from it he (Mourinho) has already won," he said.
"I award him his own personal Champions League for that, that he can take home and enjoy.
"We will simply go out on the pitch tomorrow and play our game. He is a magician at this and I don't want to play at making insinuations continually."
The return leg is on May 3 at the Nou Camp and the successful team will play English Premier League leaders Manchester United or Bundesliga side Schalke 04 in the final at London's Wembley stadium on May 28.
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