The French central defender was forced off at the Bernabeu with a hamstring injury midway through the first half.
It was a frustrating setback for the 25-year old after his return to action following a long-term knee injury.
Speaking at his pre-match press conference ahead of Sunday’s Carabao Cup final against Aston Villa, the City manager revealed that he was hoping Laporte could be fit to return towards the end of March.
“He has a hamstring injury, it should be three weeks or a month - more or less,” said Guardiola.
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“(Is it frustrating?) It is tough, but we have to be calm in the situation. Life is tough. The challenge is to accept it, to work harder and then come back in a better condition.”
Meanwhile, looking ahead to the showpiece occasion against Villa, Guardiola said he was braced for a tough challenge from Dean Smith’s side as City seek to make it a hat-trick of League Cup wins.
And the boss declared that he believed it could be a spectacle to fit the grand occasion with City looking to kick on following our historic 2-1 Champions League win away at Real Madrid.
“They are organised, with a keeper with excellent experience in Pepe Reina.
“It was a good game when we went there in the league. We will prepare the game tactically, mentally, it is a big opportunity to do something special with our club.
“The result is in the past, we are focusing on the final. It is a different competition
They have won a Champions League and they have a fantastic history. It will be a fantastic game.
“But we want to fight for another trophy.”
In the wake of that superb result and display in the Spanish capital, the boss said that confidence was understandably high in the squad.
But Guardiola also stressed that his players remained humble and focused on the task in hand.
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“The confidence it is much better, after a good result in Madrid but we cannot go to the final thinking it is done. It is incredibly difficult to beat big clubs twice, it doesn’t often happen,” the City manager added.
"The margin in a knockout competition is so tight. The decisions from Zinedine Zidane (the other evening) were perfect, it is just little things.
“We need to be calm as a team, we know that it is not over. It (the second leg) is in three weeks, before that we have the final, then Sheffield Wednesday in the FA Cup then back in the Premier League.
“We need to stay focused.”