The former Porto coach had an acrimonious parting with Chelsea in Sept 2007 before arriving at the San Siro in June 2008 to claim the Serie A title in his first season.
Related ArticlesMilan join the chase for Nemanja VidicHargreaves out of United Champions League plansBeckham ready to face Man UnitedElection debate fixture clash with Champions League footballBeckham: I won't quit football after World CupDavid Beckham didn't want to leave UnitedThis season the Nerazzurri are once again top of the table, nine points ahead of city rivals AC Milan having lost just two league games all season.
Their Champions League form in qualifying for the knockout stages was less than impressive, though, the team managing just two victories and three draws to see them pitted against Carlo Ancelotti's team with the first leg at the San Siro on Feb 24.
However, the 47-year-old believes little has changed since his departure having returned to west London in December to watch Chelsea take on Fulham.
Mourinho said: "The last time I was there I was watching all the details with attention.
"Even the warm-up is the warm-up they did in our time. The way they defend set pieces is exactly the same. The position they have on set pieces is exactly the same.
"Sometimes they play a 4-4-2 diamond, sometimes they play 4-3-3, which are exactly the systems we worked when there.
"I think it's a quality of a good coach - and Ancelotti is a good coach - to understand how the players feel most comfortable. And instead of making crazy changes, just fine tune, which is normal to keep a winning structure. I think Ancelotti's a very good coach and the team feels comfortable this way. And the team really is top - one of the best teams in the world."
He added: "When I look at that team only Ivanovic and Anelka are not players from my time. All the other boys: Petr Cech, Carvalho, Terry, Ashley Cole, Essien, Mikel, Drogba, Malouda, Joe Cole, Kalou; all of them are boys from my time.
"So it's a team without secrets for me. But at the same time I think I'm a coach without secrets for them. It will be easy for me, but I think also easy for them. I know them, but they know me. I know the way they play, the way they think, but at the same time they know the way I coach, the way I prepare my teams."