Former F1 doctor Gary Hartstein has played down renewed hopes about Michael Schumacher's health.
The seven time world champion's wife Corinna had triggered optimism last week by appearing smiling and happy at an equestrian event, before telling a German magazine that her husband is "slowly improving".
Hartstein, however, has been a regular critic of the Schumacher camp's media management of the former Ferrari and Mercedes driver's brain injuries, in the wake of his life-threatening skiing fall late last year.
Schumacher, 45, is currently recuperating at a rehabilitation clinic in Switzerland, but Hartstein said: "Unfortunately, it is extremely unlikely that things with Michael are as good as everyone hopes.
"It is realistic that Corinna is getting in touch with him in some form. But anything beyond that would be a miracle," he told the German magazine Bunte.