Having already won Group C, there is nothing at stake for City as they host the French side at the Etihad Stadium.
Manager Guardiola has indicated he will make wholesale changes for the game but he insists this has nothing to do with Saturday's trip to Old Trafford in the Premier League.
To Guardiola, squad rotation is more about ensuring all members of the squad get minutes to retain sharpness than resting players.
"I don't rest players," the former Barcelona boss said. "Our team who are going to play (on Wednesday) can play against United and then the guys who don't play (on Wednesday) maybe they'll play again or not. I don't know.
"There is not one team for one competition and one for another one. It is important the last few days that, except for one or two players, everybody was involved. Everybody has to be ready."
Sergio Aguero could be involved for City as he nears a return from his latest injury setback.
City's record goalscorer has endured a troubled recovery from knee surgery in the summer.
The 32-year-old missed the end of last season and the start of the latest campaign before his comeback was interrupted by a hamstring injury. He has then missed the last three games after suffering further discomfort in the knee.
Aguero's potential availability raises the prospect that he could feature in the derby.
Guardiola said: "Maybe he is on the bench. We are going to do a training session and see how his reaction is in his body, not just his knee.
"The important thing is the last two, three, four days he was part of the group in training and his reaction and the niggles he had in the recent past (have) disappeared."
The Marseille clash is not completely a dead rubber with the visitors hoping to claim a place in the Europa League.
Porto have already claimed the runners-up spot but Marseille can take third if they can better Olympiacos' result against the Portuguese side.
Guardiola said: "We're going to play the game to win the game. We're not thinking anything else than to win.
"It is the best way to prepare for future fixtures and we respect Marseille and Olympiacos."
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