The reigning Premier League champions were just moments away from reaching their second consecutive Champions League final, before they were left stunned by Rodrygo's late double.
Karim Benzema then scored from the penalty spot five minutes into extra-time to complete one of the most remarkable turnarounds in the competition's history and book their place in Paris, where they will meet Liverpool on May 28.
Messi couldn't believe what he was seeing on Wednesday night, as he texted former City striker Aguero his thoughts after the third goal went in.
Aguero, streaming live on the match on ESPN Star alongside former City team-mate Carlos Tevez, revealed that Messi sent him a message which said: "Stop f***ing around! It can't be!"
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