Nicola Legrottaglie spent the night in hospital and will be out of action for a week with whiplash, while Daniele Bonera also misses Milan's next match.
The Rossoneri had a very unlucky evening for their centre-backs during the 0-0 draw with Lazio on Tuesday.
Bonera went off at half-time with a badly bruised cheekbone and eye following a clash with Libor Kozak.
His replacement, Legrottaglie, was then stretchered off after accidentally getting a knee to the head again from Kozak.
“Bonera suffered trauma to the left cheekbone without fractures and trauma to the left eye socket,” read an official club statement from chief medic Dr Gianluca Melegati.
“Legrottaglie suffered trauma and a cut to his forehead that required stitches, plus whiplash to the neck.
“The first tests were negative. Tomorrow the player will undergo further tests on his neck and based on those results we can predict his return to football.”
Legrottaglie spent the night in hospital under observation and was released today. He is expected to be out of action for at least a week.
Because of this, today's planned Press conference for new buys Legrottaglie and Didac Vila was postponed.
Milan also unveiled their updated Champions League squad with Legrottaglie replacing Ronaldinho.
New signings Urby Emanuelson, Mark Van Bommel and Antonio Cassano are unavailable due to being cup-tied.
Pippo Inzaghi retains his spot in the list despite expecting to be out for the rest of the season following knee surgery.
Milan squad: Abbiati, Amelia, Roma; Nesta, Papastathopoulos, Legrottaglie, Oddo, Jankulovski, Zambrotta, Bonera, Thiago Silva, Yepes, Antonini; Gattuso, Seedorf, Flamini, Abate, Pirlo, Ambrosini, Strasser, Boateng; Inzaghi, Ibrahimovic, Pato, Robinho