While the seven time world champion circulated at Valencia on Monday, the jury was still out as to whether his neck injury is now fully healed.
The German, who had to call off his return for Ferrari last summer, travelled to the Spanish circuit for the first test of the winter with his personal doctor Johannes Peil.
Also present, and staying with the 41-year-old in his paddock motor home this week, is his physiotherapist Kai Schnapka.
Some reports referred to “secret tests” on his neck after 40 laps in the new Mercedes W01, while Dr Peil said when asked about the injury: “I’m superstitious, so we wait and see.”
Schumacher’s pace was unaffected, as he lapped six tenths quicker than Nico Rosberg, although his teammate was struggling with too low a driving position.
Germany’s Bild newspaper said there had been no problems with Schumacher’s neck.
Schumacher’s absence from the cockpit on Tuesday is planned, and he will return to action for the final day on Wednesday.