Claude Puel is delighted seeing the progress of William Saliba at Arsenal.
Puel coached Saliba at St Etienne.
He told The Sun: “You see that game against Liverpool, [Saliba] was one of the best players on the pitch. He is young, but all the ability to play in top, top teams.
“I think he is one of the best in Europe, in the world, right now.
“I remember, I put him in the team alongside Wesley Fofana, now at Chelsea. They were perfect together. It was a pity we could not keep those two for a couple more years.
“Of course, it was not possible. Saliba was an Arsenal player and we had to sell Wesley to Leicester because it was a difficult financial time for the club."
Arsenal boss Mikel Arteta famously refused to add Saliba to his senior squad for an extended time, instead leaving him away on-loan.
Puel explained: “[Arteta] decided not to pick him because he was too young, but at this time he was in a good position to win his place at Arsenal. He would have played, no problem.
“He was ready to compete. Perhaps they didn't see enough of him during his games at St Etienne. [Saliba] was frustrated. He felt that he was at a good enough level.
“But, he kept a good mentality to show his quality with Nice and Marseille. He is a fantastic player but also a fantastic man also. Very, very interesting for a manager to manage him.
“He is a simple man. He doesn't change. He always keeps a good attitude and has a good mind and feeling about his work as a professional player.
“He still has the same mentality now, even after his back injury at the end of last season."