Messi shocked the footballing world last summer when he joined PSG on a free transfer after Barcelona were unable to put their finances in order to retain his services.
That transfer remains the only one in the seven-time Ballon D'or winner's illustrious career and Leonardo is glad to have played a role in that.
Leonardo told L’Equipe: “We had thought about it a lot, yes. We had talked about it, but Messi had never thought too much about leaving Barcelona.
“It was the last moments before his arrival that were decisive. Afterwards, everything becomes a bit more normal but, you made Messi's only transfer in his career!
“Chronologically, there is Pele, Maradona, Messi. He is on Olympus. So when I take stock of my three years, I see a Champions League final, a semi-final, the 10th league title, seven national trophies and I signed Messi.”
Messi scored just 11 goals across all competitions in his debut season in France.
Leonardo went on to add of his fondest memories at PSG: “There are two very significant moments for me, even if I don't like to pick out the best.
“The first is the signing, on the same day, of [Marco] Verratti and [Zlatan] Ibrahimovic (in 2012). It was no coincidence that a youngster from the Italian second division and a world football star arrived at the same time. The second is Messi. These are two huge dates.”
