PSG top Group C on 10 points from four games, three ahead of their Greek opponents whom they beat 4-1 in the opening game, and need a draw to reach the knockout stage.
A victory would secure a top spot finish for PSG, who extended their unbeaten run in all competitions to 34 games with their 3-0 win at Stade Reims in Ligue 1 over the weekend.
"It was the best possible way to prepare our Champions League match," coach Laurent Blanc said after his side's latest demonstration of their collective force.
"Yes, some day, PSG will be beaten. The later the better," he added. "We can't say that nothing will happen to us. But our players are at their best both individually and collectively. This team have shown its strength."
Forward Jeremy Menez, who scored the second goal at Reims, said PSG were strong enough to control the outcome of their games.
"Are we beatable? If we loosen our grip, maybe. But if we keep putting all the ingredients, we're really tough to play against," he said.
At Reims, the last team in Europe to have beaten PSG in March, former France coach Blanc rested some of the players coming back from international duties.
Defender Maxwell, midfielder Blaise Matuidi and forwards Ezequiel Lavezzi and Edinson Cavani were all benched while full back Gregory Van der Wiel sat in the stands.
They are all expected to start on Wednesday in a full-strength PSG team that will count on leading-scorer Zlatan Ibrahimovic.
The in-form Swede, who have netted seven in four Champions League games, set up the opener and closed the scoring on Saturday, proving he had moved forward after failing to help his country qualify for the World Cup.
Olympiacos, however, are not expected to be an easy prey as Michel's team bubble with confidence after their superb run of recent form.
Since losing to PSG, the Reds have been unbeaten in Group C and took a firm grip on second place with a 1-0 win over Benfica last time out.
In the Super League, they have been virtually unstoppable, winning 11 out of 12 matches while recording one draw.
A 4-1 away win over Panthrakikos on Saturday has added to the confidence of the Piraeus club, and left-back Jose Holebas insisted beating PSG was not impossible.
"In the Champions League you have to respect all the teams as anything can happen as has been proven time and again," said the Greece defender.
"If we go out and play with our heart and stay focused, although it's a tough match, we can get a good result. Of course in Paris they have many great players who can cook even just with water as their only ingredient. Let's see what we can do, I believe we can even beat them."
Holebas singled out in-form team mate Kostas Mitroglou for praise as the 25-year-old striker continues to find the net for club and country.
"With Mitroglou up front I think we can score in Paris," Holebas said. "He can't stop scoring at the moment but he also keeps the ball well and this allows us to push other players forward and create chances."
Mitroglou, Giannis Maniatis and Holebas were all rested at the weekend in preparation for the match in Paris.