The 46-year-old, who started his playing career at the Catalans before joining the Blancos, favours the champions to win, while praising David Villa following his comeback
The Catalans proved to be the stronger side last season after successfully defending their lead in the return at Camp Nou, but Milla believes Madrid could come out victorious this time around.
"Madrid have the advantage because they are playing the return at home. Both teams are pretty similar, though. Barca might have changed coaches, but their philosophy remains the same," Milla was quoted as saying by Sport.
The 46-year-old then went on to express his delight with David Villa's return to match action, and stressed that the attacker can play a key role for Barca.
"The most positive thing is the return of Villa. He is a decisive player because of his goals, and his character will be very important for the team's morale. He has status and is a guarantee for 25 goals if he's fit."
Thursday's first leg at Camp Nou kicks off at 22:30CET.