World at his feet: Boateng (right) is going to South Africa
The 21-year-old expects to formally complete his £10.5million move this week, signing a four-year contract with the ambitious Barclays Premier League side before jetting out to the World Cup as part of Germany's squad on Sunday.
He was part of an ambitious Hamburg side, who signed Ruud van Nistelrooy in the winter and were looking to reach the Europa League final at their home stadium.
But events off the pitch persuaded Boateng that his future lie away from the Nordbank Arena, where coach Bruno Labbadia was sacked and replaced by former Tottenham fitness coach Ricardo Moniz just three days before the European exit at the hands of Fulham.
'I didn't like it any more,' Boateng told SportBild. 'Everything fell apart in the second half of the season.
'Things weren't great in the team. One thing would be said in public, while the others talk about you behind your back.
'There are things that have happened that have made it easier to make my decision.'
Boateng believes his team suffered overconfidence in their pursuit of the Bundesliga title and eventually finished a disappointing seventh.
Red marauder: Boateng (right) was a rock in the Hamburg side
When City moved to complete a deal that was first revealed by Sportsmail in the spring, it took Mancini to set out his vision - and promise Boateng his favourite No 17 shirt - to sway the four-year deal.
'Before going to the World Cup I'll probably sign and announce the transfer,' he said. 'It is decided that I will go there.
'He (Mancini) was with two representatives of the club in Hamburg. We talked for two hours and he encouraged me to go.
'He said I would certainly need a month or two to get used to being in England. But he sees so much potential in me, and he will make me into a better player.
'Bayern were also interested, but there were no negotiations or advanced talks.
'Even though many people tell me I will struggle to be successful, I have confidence in myself. Nothing scares me, and I need a new challenge.'
Public enemy No 1: Kevin-Prince Boateng (left) tackles Ballack in the Cup final
First comes the World Cup and a potential group stage showdown with his half-brother Kevin-Prince, the Portsmouth midfielder who chose the Ghana national team after playing for Germany at youth level.
The Boatengs have been subjected to a witch-hunt after Kevin-Prince's tackle in the FA Cup final injured Michael Ballack and put the Germany captain out of the tournament in South Africa.
Jerome, in World Cup mode, admits he's not currently in touch with his sibling, and is smarting that his family were dragged into a media storm.
'I currently have no contact with Kevin,' he said. 'We both go our own way. He does his thing, I do mine.
'What disturbs me is how our name was dragged down in the public domain and our family wasn't left alone. Suddenly everyone is tarred with the same brush. My big brother had cameras at his door and is under siege. There are lines that have been crossed. It's unbelievable.
'Everything went too far. This can't be - the fact that my family can't even go to a cafe in peace, that my brother and his children can't play in the garden in peace. Where are we then?'
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