Fleck, 17, was dropped from the first-team squad for the Emirates Cup in London, as the Scottish champions suffered a 3-0 defeat to winners Arsenal.
Boss Walter Smith revealed afterwards that he made the decision to send the talented teenager to Northern Ireland with the reserves before a reported bust-up with assistant manager Ally McCoist.
However, Novo has warned the youngster he will have to knuckle down and work hard if he wants to succeed at Ibrox.
"John Fleck is a great young player and he can do it for Rangers," said the striker. "He can do whatever he wants to do in the game with the ability he has. I think he has the ability to become a very good player.
"The quality is there - now it is about how he is going to do it and what he can do with his talent. I think for every player it is vital to work hard.
"A strong mentality and working every day is what you need to do.
"This is what all the senior players will tell John. He has all the talent but you need to keep working hard."