The two forwards look set to miss the high-profile Champions League clash due to knocks picked up in training
The 29-year-old suffered an adductor injury during the final practice session before the squad was set to head out for Spain and was left behind as his team-mates boarded their afternoon flight.
Club CEO Adrian Galliani was not overly upset by the news though, telling reporters: "I'm not crying about it. It's not a knockout game, there will be others. [Alexandre] Pato and [Antonio] Cassano, two champions, will play."
The club website also confirmed that Milan will give Ibrahimovic a few days to recover before he returns to full training.
And the Swede may not be the only absentee for the Serie A champions as Robinho didn't make the final squad for tomorrow's clash at Camp Nou after reportedly picking up a muscle problem in training.
The two injuries will act as a serious setback to coach Massimiliano Allegri's hopes of gaining something from the trip to face the European champions, with Pato and Cassano now likely to start up front.
However, the Italian side have received some good news with the returns of Gianluca Zambrotta, Clarence Seedorf and Taye Taiwo.
The Group H clash takes place on Tuesday evening, kicking off at 20.45 (CET).