Rafa Benitez says Southampton will have an "advantage" over Newcastle United at the St Mary's Stadium.
The two clubs face each other on Sunday in a televised Premier League game.
And Benitez says Southampton manager Mauricio Pellegrino will have an edge in the dugout – having played for and coached alongside him.
Pellegrini played under Benitez at Valencia and Liverpool before joining his coaching team at Anfield.
The Argentine – who succeeded Claude Puel at Southampton in the summer – also joined his backroom team at Inter Milan.
Newcastle manager Benitez said: "He was my player in Valencia for two years when we won the league and UEFA Cup.
"I brought him to England to help with the defence, and after he was my assistant in Italy. He went to Argentina and last year he was in Alaves and doing well.
"He's someone who has always been focused and worked hard. He likes football and likes to study and learn.
"He knows everything about me, because he was my player and assistant. He has an advantage, but at the same time we know him really well too.
"It's a special situation. If you wanted to say something or change something, he would know already.
"Players don’t analyse the game, but when you are a coach you know tactics and how people prepare for a game. He will have an advantage, but we will have that advantage too."
Benitez always felt Pellegrino was destined for a career as a coach.
“When I was at Valencia we had a group of Argentina players, and after lunch they would talk about football for hours," he said.
"He was one of them. Normally, if you are like that, you will finish as a coach or a pundit, you could see from the beginning that he would be a coach. We were talking a couple of weeks ago, but not this week."