The Greek champions stunned their English counterparts in the UEFA Champions League last 16 first leg with goals either side of half-time from Alejandro Dominguez and Joel Campbell, taking advantage of yet another lacklustre performance from United.
While Michel was thrilled with the win against such a prestigious opponent, the Spanish coach was quick to remind Olympiacos that the job is only half-finished.
"To beat a great side like United in the manner we beat them is very special. I can't hide my joy," Michel said.
"I feel proud of my players. It was a great moment for us.
"But we must look ahead to the second leg. We still have the match at Old Trafford. We expect a different United at Old Trafford, we have huge respect for them.
"Anyone who thinks 2-0 is enough to qualify is mistaken. 2-0 is not enough to get through against United at Old Trafford. We have to keep on working to make it through and make history."
Olympiacos have only qualified for the UEFA Champions League quarter-finals once before in the 1998-99 season.
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