Milan were on the ropes before their stunning 3-2 win at Real two weeks ago and now look favourites in the reverse Champions League Group C fixture.
Fans of the Serie A club were shattered by the sale of the Brazilian and a dreadful start to the season, including a 1-0 home defeat by FC Zurich, made them feel even worse.
However, a switch to a 4-3-3 formation has since worked wonders and Leonardo's side are unbeaten in seven games.
"Real is a game which you especially prepare for. We hope to maintain our high level of play," Leonardo told reporters after Saturday's 2-0 win over Parma.
Striker Marco Borriello, fit after a year out with a back injury, was set up by Ronaldinho to score both goals but faces a battle to stay in the side with European maestro Filippo Inzaghi, 36, waiting in the wings.
Only one of the target men is expected to start on Tuesday with former Barcelona forward Ronaldinho set to play on the left of the front three and Alexandre Pato, who netted twice at the Bernabeu, poised for the right.
Former Real striker Klaas Jan Huntelaar is therefore likely to stay on the bench while centre back Alessandro Nesta hopes to return after missing the Parma match with a thigh problem.
TURBULENT WATERS
Real, level with Milan at the top of the group with six points from three matches, managed to calm the turbulent waters at the Bernabeu with a 2-0 La Liga win over Getafe on Saturday.
The victory was all the sweeter as it was achieved with 10 men, won over sceptical home fans who had started the match whistling the side after three games without a win, and put them one point short of league leaders Barcelona.
Their embarrassing 4-0 defeat by third-tier Alcorcon in the King's Cup last week meant calls for coach Manuel Pellegrini to go reached hysterical levels in the local media.
President Florentino Perez has moved to back the Chilean.
"The papers have been full of names of great coaches but we are happy with Pellegrini and we are sure he will finish the season positively," he told Italian television.
Pellegrini is still without Cristiano Ronaldo because of an ankle injury but striker Ruud van Nistelrooy has been included in a Champions League squad for the first time this season.
Raul will become the record goalscorer in European club competition with a goal on Tuesday.
Probable teams:
AC Milan: 1-Dida; 44-Massimo Oddo, 33-Thiago Silva, 13-Alessandro Nesta, 15-Gianluca Zambrotta; 23-Massimo Ambrosini, 21-Andrea Pirlo, 10-Clarence Seedorf; 7-Alexandre Pato, 9-Filippo Inzaghi, 80-Ronaldinho
Real Madrid: 1-Iker Casillas; 4-Sergio Ramos, 3-Pepe, 18-Raul Albiol, 2-Alvaro Arbeloa; 24-Esteban Granero, 22-Xabi Alonso, 10-Lassana Diarra, 8-Kaka; 7-Raul, 11-Karim Benzema
Referee: Felix Brych (Germany)
