كتب : Omar AbdelAziz
Andrea Pirlo's thunderous first half strike was cancelled out with a similar effort from Maximiliano Perreira a few minutes later.
The Rossoneri have 10 points on top of Group D, while rock bottom Benfica have four points and their hopes are now limited to reaching the UEFA Cup.
On-fire midfielder Pirlo collected Kaka's pass to score the opener after 15 minutes with a marvelous long-range drive.
However, Milan's lead lasted for five minutes as Perreira beat Dida with a left-footed effort from 25 yards.
Dramatic Winner
In the other group match, Celtic came from a goal down to beat Shakhtar Donetsk 2-1 thanks to a last-gasp killer goal from substitute Massimo Donati.
The Italian hit the winner in the dying seconds after Jiri Jarosik equalized for Celtic, following Brandao's early goal for the visitors.
Brazilian forward Brandao scored his fifth of the competition four minutes from the start when he cleverly slotted home past Arthur Boruc.
However, Czech midfielder Jarosik grabbed a priceless equalizer just before half-time, slamming home a magnificent left-footed volley.
Former Milan midfielder Donati won the game for the Bhoys with a deflected injury time shot from 12 yards out.
Celtic's victory put them in second place with nine points, while Shakhtar come third with six.