Sergio Perez will make a decision on Friday morning about his fitness for practice at the Indian Grand Prix, after returning to his hotel early on Thursday because of illness.
The Sauber driver has been struck down by a bad cold, and he elected to skip his media commitments at the track so he could get some extra rest.
Perez's illness is not thought to be serious enough to cast doubts about his participation in the event, but the team is not ruling anything out.
If Perez is too unwell to take part, then Sauber will call up its reserve driver Esteban Gutierrez to compete.