The Argentine flew from his homeland on Tuesday night after the two clubs struck the multi-million deal, and took to social networking site Twitter on arrival.
He wrote: 'Just landed in Manchester to finalize the details of the offer with the City. Everything is fine! In a while I'll tell you more.'
Blue move: Aguero is keen to finalise his move to City and refused to return to training with Atletico
It is understood City already have a clear idea of his personal demands and do not expect discussions to take very long.
The highly rated 23-year-old is expectedto put his name to a five-year contract worth around ?200,000 a week and his arrival will certainly please manager Mancini.
City are expected to lose Carlos Tevez in the coming weeks and with doubts remaining over the reliability of Edin Dzeko and Mario Balotelli, Mancini needs a proven goalscorer before the Barclays Premier League season begins in two-and-a-half weeks.
Aguero has recently played with his compatriot Tevez in the Copa America and as such will be allowed some holiday before beginning his new life at the Etihad Stadium.
Adding to the ranks: City boss Mancini is hopeful of completing a deal before the squad visit Ireland
Tevez has been told to report back for training with Mancini's squad on August 4 and the same will apply to Aguero, meaning neither player is expected to start in the Community Shield against neighbours and rivals Manchester United three days later.
City travel to the Republic of Ireland on Friday for two games in the Dublin Super Cup, including the pick against Inter Milan on Sunday.
City's deal with Aguero is thought to have been sealed after the striker talked the move through with his wife Giannina, who is Diego Maradona's daughter, in Argentina over the weekend.
Tough times: Carlos Tevez dream of a return to South America was lost at the 11th hour
Source: Daily Mail
Source: Daily Mail