The 19-year-old is poised to complete a move to Pep Guardiola's side in the coming days, with Atletico Nacional coach Reinaldo Rueda confirming that a transfer is imminent.
Moreno has long been linked with a move to the Etihad Stadium and Sportmasta understands that City are poised to announce the signing of the 19-year-old in the coming days.
The Atletico forward is one of the brightest young talents in South American football, showcased by his efforts at the Copa America Centenario with Colombia.
And Rueda has now confirmed that Moreno's Premier League transfer is imminent, pending a few minor details to be ironed out in the coming days.
"Everything with Marlos is very close," the 59-year-old said.
"It is a decision that has already been made by his agent and representatives."
However, with Atletico set for the return leg of their Copa Libertadores semi-final with Sao Paulo on Wednesday - in which they hold a 2-0 advantage - Rueda is hoping Moreno remains focused on the task at hand.
"We need and I hope he does not isolate himself from our goal [of reaching the final]," the coach added.