The 66-year-old rocker had an operation this week at L.A.’s Cedars Sinai hospital to fix lingering back trouble from a Nov. 26 operation in Paris for a herniated disc.

Separately Saturday, the lawyer for the French doctor who first operated on Hallyday said two masked men attacked Dr. Stephane Delajoux overnight in Paris. The physician was roughed up but not hospitalized.

Hallyday producer Jean-Claude Camus told France’s TF1 television that Hallyday was put in a coma “so he won’t suffer,” and the outlook was positive.