City told Hart and England teammate Gareth Barry they did not have to return until the New York leg of the tour next weekend.
But Hart is desperate to prove himself to Roberto Mancini and with Shay Given set to miss the start of the season through injury, the 23-year-old is heading for Portland, where City play a practice match this weekend.
This reflects very well on Hart. It was clear as soon as Birmingham City bought Ben Foster that Hart would be competing with Shay Given to be first choice in 2010/11. Which means that one of them is going to be disappointed. And with Given's shoulder injury jeopardising his early-season availability, Hart could well start the season as first choice.
I used to be unthinkingly pro-Given, but the more I think about it the more open I am to Hart being first choice. Ideally we'd have another year of Given and then Hart from 2011/12 onwards. But why not now? If he's good enough he's old enough and all that.