Liverpool gave the Blues a scare before the interval.
Baros forced an excellent save out of Cech on 39 minutes when his international teammate tipped a powerful header round the post following a curling Steven Gerrard pass.
Cole gave Traore further trouble five minutes after the interval, but after cutting inside the left-back, Sami Hyypia slid in to nudge the ball from his feet as he shaped to shoot.
Liverpool's Igor Biscan and Chelsea's Cole were cautioned as tempers flared before Netherlands winger Robben replaced Tiago with 31 minutes left.
Benitez responded by replacing Baros with Cisse in the lone striker role. The France forward blasted a fierce shot just wide on 68 minutes, leaving Luis Garcia bemoaning the spurned chance to cross.
Liverpool sensed the opportunity for a vital away goal and surged forward whenever possible. That tactic left defensive gaps to exploit and Blues striker Mateja Kezman came on for Cole with 13 minutes left to try and exploit them.
Liverpool's Xavi Alonso was cautioned in the last few minutes to rule himself out of the return leg.
A goalless draw seemed to suit Benitez, who sent on Vladimir Smicer for Luis Garcia in the dying seconds to run down the clock.
Cech had to charge off the goal-line in injury time to deny a Cisse effort, securing a stalemate for the trip to Merseyside next Tuesday.
AC Milan 2, PSV 0
AC Milan beat PSV Eindhoven 2-0 in their Champions League semifinal, first leg on Tuesday with a first half goal from Andriy Shevchenko and a last minute strike from substitute Jon Dahl Tomasson giving the Italians a great chance of a place in the final.
Shevchenko gave Milan the lead after 42 minutes at the San Siro when he latched on to a through ball from Kaka and outpaced Wilfred Bouma before firing past PSV's Gomes from 10 meters.
Danish striker Tomasson wrapped up the victory in the last minute after PSV seemed to have done enough to give themselves a strong chance in next Wednesday's second leg in Eindhoven.
PSV created a number of openings in their impressive performance and made it tough for Milan but Tomasson's late strike leaves Milan favorites to reach the final in Istanbul on May 25.
It was Milan's seventh successive Champions League match without conceding a goal -- a new record for the competition -- but without the suspended Alessandro Nesta their defense was uncharacteristically shaky against a pacey PSV attack.
Milan made a positive start and Shevchenko had a chance in the second minute when skipper Paolo Maldini picked him out with a diagonal, cross-field pass but the Ukrainian shot meekly at PSV's Brazilian keeper Heurelho Gomes.
Clarence Seedorf and Hernan Crespo both forced saves out of Gomes during an intense spell of opening pressure from Carlo Ancelotti's side.
But they soon got a warning of the threat that PSV pose on the break when Peruvian striker Farfan tested Dida with a low shot that the Milan keeper uncomfortably fumbled out.
The pace of South Korean Ji-Sung Park and American DaMarcus Beasley were causing Milan's defense some problems but the Italians soon got off the back foot and restored their control.
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