Ronald Koeman says £47.5 million former Everton defender John Stones is "part of the philosophy" of Manchester City boss Pep Guardiola.
On Saturday, the Dutchman will come up against the defender who left the Toffees in a record domestic deal for a defender - before he could play under him.
And Koeman believes he is the ideal player for his former Barcelona teammate Guardiola.
"John Stones is part of the philosophy of the coach," he said.
"One of the good qualities of John Stones is that he is that player who can open the game and provide that passing they need from the back."
Koeman has called on his "key players" to start producing and believes there is no better time than against the current Premier League leaders.
"We have some key players in the team and they need to bring productivity to the team and we can improve on that," he said.
"We know we can be better than we are at the moment. Of course, the last two or three results, including the cup game, were not what we expect but we know we are Everton and we don't win every game.
"We are in a good way but we know we can be better than we are at the moment.
"It is difficult because we did not have the players for training the last two weeks and it's always difficult to have that focus that you need to beat City."