Lennon will be hoping his side can fare better than on their last visit to Italy, which ended in a 2-0 defeat to Juventus en route to a 5-0 aggregate loss to the Serie A champions in the last 16.
And the Celtic manager is counting on his inspirational skipper who missed the majority of last season's European campaign due to niggling injuries.
"Scott is outstanding at the minute," said Lennon.
"He is playing so well. He's injury-free and when you think that we have lost Gary Hooper, Victor Wanyama and Kelvin Wilson in this summer, to have a fit Scott Brown for the Champions League, which we didn't have last year, is going to make us better."
AC Milan have major injury concerns of their own ahead of the game with Riccardo Montolivio out due to a thigh injury and fellow midfielder Andrea Poli doubtful also with a thigh complaint.
Strikers Stephan El Shaarawy and Giampaolo Pazzini and defenders Ignazio Abate and Daniele Bonera will also be absent for the Italian giants.
Group H is the only section in this year's competition to contain four previous winners of Europe's Elite competition.
The other group match on Wednesday sees last year's beaten semi-finalists Barcelona entertain Ajax at the Nou Camp.