Tuchel wants to see Grealish playing consistently ahead of next year's World Cup.
He said: “I love Jack for his personality and of course his talent. He is a very unique player who can handle big pressure on the field.
“He is never shy of pressure. It’s the opposite. He grows in big matches but he’s a player who needs minutes and minutes and minutes and simply does not get them for a very long time. That’s basically everything. Nothing has changed.
“I have maybe the same information as you that City are thinking of not taking him to the Club World Cup. So he needs to make himself available by playing. I think it’s one of his key strengths.
“To go every three days and get better and better with every minute that he has in his legs. That’s what is missing, nothing else. I have spoken to him after the first international camp and very shortly after the FA Cup final but not since then.”