The France defender has been struggling with a calf injury sustained during Sunday's Ligue 1 encounter with Paris Saint Germain.
Guy Roux will hand the 22-year-old a late fitness test before deciding whether to pitch him into the action.
"If the match was played on Tuesday, Mexes would have given up," conceded Roux.
"He has nothing broken.
"If he is fit, he will play.
"When I have an injured player, I don't complain. I just replace him."
With Jean-Alain Boumsong also injured, it leaves Roux with a major headache over the centre of his defence.
Mexes has been an ever-present so far this season and will be desperate to be involved against Auxerre's Greek opponents.
