The English defender looks forward to the decisive game in the group stage of the Champions League, as the Reds visit San Siro on Tuesday night.
The Sweden striker, who turns 40 in October, has been credited with turning Milan into title contenders again since his return to the club in January last year.
Tomori was struggling for game time under former Blues manager Frank Lampard and headed to San Siro on loan in January, where he has made an immediate impression.
Tomori has joined the Rossoneri on-loan to the end of the season with a permanent option included for €30 million.
The Swede becomes the second Rossoneri player to test positive this week after Leo Duarte.
Zlatan Ibrahimovic is determined to have an impact in his second spell at Milan, saying he is not back at San Siro to join Milanello the mascot on the sidelines.
The Nigeria U23 international was apparently a target for the Rossoneri in January, with the player himself claiming he rejected a move to San Siro.
Arsene Wenger, who has been linked with Milan, admits “I feel frustrated” not to be working after leaving Arsenal.