The Italian giants lead 2-0 on aggregate courtesy of goals from Kevin-Prince Boateng and Sulley Muntari at San Siro three weeks ago, but Max Allegri's men still have a considerable task ahead to ensure the Rossoneri are in the pot for Friday's draw for the quarter-finals.
And Barca legend Suarez says success hinges on how they perform for the first 30 minutes.
"It will not be easy for Barcelona. The 2-0 result is dangerous. Everything depends on the first half-hour, if Barca can score a goal. If they do then the tie will be within their grasp and they will be able to play with more ease," Suarez told La Xarxa Radioon Monday.
“Milan are dangerous, they are fit, physically good. Barcelona have their style of play and must continue with that, they cannot change their style for one game.
“The thing they have to do is see that everyone in the team has a great game. In these European Cup games you have to play to your death.”
Suarez was a prominent figure for the Blaugrana between 1955 until 1961 and has offered his sentiments on a potential future star at Camp Nou, Neymar, and believes the starlet is tailor-made for the Barca experience.
"Neymar has a way of playing that can be perfectly adapted to Barcelona," he added.
"Players who come to Barcelona cannot be just good players, but they have to adapt to a style of play that is not easy."