Michael Essien started the match on the bench and saw midfield rivals Frank Lampard and Michael Ballack both get amongst the goals in the 3-0 victory.
"I don't think I can keep everybody happy for a long time because sometimes players that don't play feel unhappy," Grant told Sky Sports News.
"I want them to play all the time, but they are happy if we win which is more important.
"It is not easy with this squad, but I prefer a squad like this than the problems I had in December or January."
"We are in the next round," Grant added. "We knew before that Olympiacos always scored away so it was important to keep a clean sheet and more importantly to score.
"When it became 2-0 and we controlled the game we kept the ball very well and the game was finished."