Leicester boss Claude Puel believes Arsene Wenger is irreplaceable as he prepares to leave Arsenal.
Puel played under Wenger at Monaco for seven years and feels it will be difficult for his replacement at the Emirates.
Wenger heads to the King Power Stadium with the Gunners on Wednesday with Juventus' Max Allegri or former Barcelona boss Luis Enrique tipped to replace him.
And Puel -- under pressure at the Foxes after a run of just four wins in 19 Premier League games -- compared Wenger's exit to when Sir Alex Ferguson left Manchester United in 2013.
He said: "I hope for them they cannot regret their choice because he has had a massive impact as manager of Arsenal for 22 years. How can you replace him?
"I think it will be a good challenge for the new manager. It is always tough like after Sir Alex Ferguson, it was tough for the manager afterwards.
"After a few years they can come back at a good level but it is difficult when a club have had success like this and replace the manager and sometimes replace valuable or great players.
"It will be difficult for the new manager. I think perhaps the new manager or great managers will like different options or possibilities to start his work.''
Puel has no plans to give his former manager a gift as Wenger leaves the Gunners after Sunday's final day trip to Huddersfield.
But he does want to welcome the 68-year-old to the King Power Stadium in a friendlier way than when the pair were on the training ground at Monaco.
"One time the ball was between him and me and I touched the ball. But behind the ball there is Arsene and he flew up in the air,'' he said.
"He fell on his back and he couldn't move. The fitness coach took him in the dressing room and I had a bad feeling.
"The other players were smiling and I was thinking in this moment 'it is finished for me and I will not play in the future.'
"It is not a lack of respect but the intensity of the training you need to have. Quickly I played the next game, it was OK. Of course he will get a friendlier welcome.''