The striker hobbled off late on during victory at Sunderland.
Giroud said: "It is not bad actually, not as bad as I first feared. I got a kick earlier in the game but no-one was near me when I did it this time.
"I tried to connect with the ball a little bit too early and I caught my foot in the grass. I twisted my ankle but fortunately, it is nothing major.
"I am OK, sure I will be fine [for Marseille]."
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