Eto'o moved to Inter in the summer after five years at Barcelona.
Mesalles told Corriere dello Sport: "I was in Madrid for Christian Karembeu's transfer to Real Madrid and the directors asked me to also assist Eto'o who didn't have an agent and needed a new contract.
"Since then I have considered him like a son of mine. The deal with Inter was born in April 2007 when I met, once in Spain and another time in Italy, with Marco Branca and my friend FIFA agent Claudio Vigorelli.
"Back then, Milan had also come forward and tried to sign him. We visited Galliani, but Barcelona didn't want to sell Eto'o.
"We spoke with the Juventus directors, but nothing came of it.
"Evidently it was destiny that he should go to Inter where he is now happy."