The upset is possible. Not likely obviously, but IMO more likely than Jo upsetting Fed on this surface.
I expect Murray to win most of the baseline rallies but Jérémy will probably try to be aggressive especially on the return. If Murray's 1st serve percentage is low, Chardy can trouble him with deep and hard returns. Combine that with a good serving day, Jérémy could be dangerous.
In this case, it will come down to how Jérémy handles the pressure if he takes the lead. From what I heard, he was pretty solid against Delpo, so it's not unthinkable.
But that's a lot of ifs, obviously.
"Nearly ever male player has a better backhand than Federer." ~ federer20042006