But Dragons coach Paul Turner is hopeful the veteran flanker will prove his fitness and shine against the three-time European kings tomorrow (Saturday).
Turner said: "We really hoped Colin would pull through because I admire the way he goes about his work. He says he's like a tin of ronseal - what you see on the label is what you get.
"I wanted him purely as a coach this season but injuries have forced him to take on more of a role than we'd have liked. I've been delighted with his overall contribution."
The Dragons launched their European campaign with a win over Glasgow Warriors before picking up a valuable losing bonus-point at English high-flyers Bath.
Now Turner reckons Charvis can inspire his team-mates to pull off a shock result in the south of France.
Turner said: "I didn't know Colin until I signed him two years ago. But his leadership qualities will add another dimension to our performances levels and that will be crucial against the might of Toulouse."