The Rossoblu supremo agreed to sell the 30-year-old Argentine to the Nerazzurri but just three hours later the Giallorossi offered €2 million more for the player
The 30-year-old's move to San Siro has not yet been made official, but both Preziosi and Moratti have spoken of the proposed transfer as if it is a done deal.
Indeed, Preziosi has now explained that he could have made even more money out of the transaction had he just held out for a few more hours.
"Roma made a bid €2 million higher than Inter's but I had shaken hands with Moratti three hours before," the Rossoblu supremo told Radio Mana Mana.
"I did everything to keep Palacio. He has had three wonderful years with us. He gave us everything from a technical and a human perspective.
"Inter don't know what a great deal they have done. I took [Alberto] Gilardino in January to form a great attack with Palacio but now what has happened has happened."
Palacio, who arrived at the Luigi Ferraris from Boca Juniors, scored 19 goals in 32 Serie A appearances for Genoa last season.