He has since joined New York City FC and has become a revelation under the guidance of Patrick Vieira.
And the midfielder could even be asked to train with Pep Guardiola's side in Manchester at some point.
“City will have first dibs on Harrison at New York if he continues his rapid progress," a source revealed.
“It's sure to rub United up the wrong way after what happened to him as a kid. He's having a great time over in the US.
“City are hearing positive things from the execs in New York and that Harrison is an exciting late bloomer."