By Clive Lindsay
Lee Naylor went close to scoring for Celtic
Yoann Gourcuff squandered an opening and goalkeeper Artur Boruc's outstretched foot prevented Alberto Gilardino giving Milan an early lead.
Kenny Miller passed up a couple of half-chances for Celtic.
But Milan were the more dangerous and Rino Gattuso and Gilardino fired wide as Celtic avoided an away goal.
Jan Vennegoor of Hesselink had come through a late fitness test to lead Celtic's attack in the first leg in Glasgow.
He was partnered by Miller, with Craig Beattie and Maciej Zurawski having failed to recover from injury.
Darren O'Dea and Evander Sno came in for cup-tied pair Steven Pressley and Paul Hartley, while Aiden McGeady replaced Jiri Jarosik in midfield.
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Milan midfielder Clarence Seedorf failed his fitness test and joined Ronaldo and Filippo Inzaghi on the sidelines.
But Gilardino was passed fit to take a lone striker role.
He was supported by Kaka and the Brazilian playmaker was first to threaten, running at the Celtic defence but driving straight at Boruc from 20 yards.
Milan legend Paolo Maldini marked his 100th Champions League appearance by picking up the first booking after a strong challenge on Vennegoor of Hesselink.
Miller had Celtic's first opportunity but fired straight at Zeljko Kalac from a difficult angle.
But 2005 finalists Milan created the first clear-cut chance, but Gourcuff sent a weak 14-yard header straight at Boruc after being found unmarked by Kaka's flighted cross.
Ex-Rangers midfielder Gattuso (left) was back in Glasgow
Kaka was again the creator, putting Gilardino clear behind the Celtic defence, but a touch off Boruc's outstretched foot was enough to turn the striker's effort just wide of the far post.
A Mark Wilson cross fell to Miller at the back post, but the Scotland striker miscontrolled and the chance was lost.
McGeady had the first effort of the second half but fired straight at Kalac from 22 yards.
But Milan were again the more incisive and Kaka picked out Gattuso, who fired wide of the post from just inside the box.
Celtic responded with their best move of the match, but a 25-yard drive from Lee Naylor curled wide.
Gilardino appeared to be clipped by Wilson inside the box, but the Italian's acrobatic dive earned a booking.
The striker fired wide then forced Boruc into a save as he began to find more space in the penalty box.
Celtic substitute Thomas Gravesen sliced wide from just inside the box as Gordon Strachan's side had to be content with a creditable draw that keeps the tie alive for the second leg in Milan.
Celtic: Boruc, Wilson, McManus, O'Dea, Naylor, Nakamura, Sno, Lennon (Gravesen 81), McGeady, Vennegoor of Hesselink, Miller (Jarosik 62).
Subs Not Used: Brown, Telfer, Riordan, Perrier Doumbe, Kennedy.
Booked: Nakamura.
AC Milan: Kalac, Oddo, Kaladze (Bonera 62), Maldini, Jankulovski, Gourcuff, Gattuso, Pirlo, Ambrosini, Kaka, Gilardino (Oliveira 77).
Subs Not Used: Storari, Cafu, Costacurta, Simic, Brocchi.
Booked: Maldini, Gilardino.
Att: 58,785
Ref: Terje Hauge (Norway)
The first leg of the round of sixteen in the  was completed on Wednesday, with at least one controversial result, and a bag full of ties.  The leg began on Tuesday with four games, and the other four were played the next day, including reigning champions FC Barcelona of Spain.

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