The former Real Madrid midfielder guided the Greek champions to the knockout stages last year, where they were undone by a Robin van Persie hat-trick as Manchester United overturned a 2-0 first leg deficit to prevail 3-2.
Olympiacos have been given a tough draw this time around, with Atletico, Juventus and Malmo making up the remainder of Group A.
First up for Michel and his team are last season's runners-up, who came close to adding European glory to their La Liga title before they were beaten in the final by arch-rivals Real in May.
And Michel knows his side will be up against it when Olympiacos host Diego Simeone's men on Tuesday.
"All the games at this stage are difficult," he said in a press conference on Monday.
"Atletico's result at the weekend against Real Madrid [a 2-1 win] shows to all of us who we are up against. I expected that result. Diego Simeone knows his team very well. He's created a real team.
"The results speak for themselves. We are fully prepared. We have the experience and we will fight for the result.
"Atletico have changed players but they remain the same powerful side. They have teamwork so changes to individual players will not change much for them.
"Each team has its style and we will play our own style and I believe we will do well. There will be no changes in our style of play. Attacking, keeping possession and defending well."
