Former Manchester City forward has implored Ross Barkley to join his old club.
The highly-rated 20-year old Everton midfielder continues to be linked with a move to City with reports suggesting the reigning premiers are ready to splash in excess of £30million in order to land their man.
Barkley, who has been with the Toffees since he was 11, is also a target for Chelsea and Liverpool but Marsh feels he will be a startling success if he opts to leave Goodison Park for the Etihad Stadium.
"I would advise Ross Barkley to move to Manchester City in a heartbeat," former QPR and City ace Marsh said.
"He has the opportunity to become one of the greatest British players we've ever seen.
"He's the sort of player who can move to Manchester City and, unlike others, can get into the first-team as a youngster, dominate and become a truly great footballer.
"I would advise anyone at the moment who has the chance of becoming a top player to go to City, it's a wonderful club now. They've got everything in their favour, from their training conditions to being able to play around great players.
"This morning I spoke with someone who has seen every game Ross Barkley has played, even for Everton's youth team. He told me this kid loves his football, he trains harder than anybody, he stays behind after training and is a wonderful young man as well, and they truly believe he will go on to become a world star.
"Another player Everton let go as a youngster, Wayne Rooney, became the biggest thing in British football when he moved to Manchester United. I put Barkley in the same category.
"Only time will tell but I think this kid can be breathtaking, both for England and Man City, if he decides to move there.
"I think Yaya Toure could well be out of the back door, so that's another reason why I think Barkley would be great at City."
