VALENCIA, Spain Marussia driver Timo Glock missed qualifying for the European Formula One Grand Prix due to illness on Saturday, making the German doubtful for Sunday's race in Valencia.
"Timo has been fighting a stomach bug since Thursday," his team said in a statement.
"He felt well enough to take part in yesterday's free practice sessions and had seemed to be improving. This morning, after free practice three, he started to feel unwell again.
"It is clear that at this time, he is not sufficiently well to take part in a demanding qualifying session and needs to recuperate further."
Glock, who has not scored a point since he left Toyota at the end of 2009, had been slowest in Saturday's session.
He could still take part in Sunday's race but that decision will depend on the race stewards as well as his team, whose other driver is French rookie Charles Pic.
"Timo and the team will now seek further medical guidance this afternoon," Marussia added.
"Until such time as this guidance has been received, no decisions will be reached regarding tomorrow's race. A further statement will be issued on Sunday morning."
Marussia do not have an official reserve driver.
Spanish woman racer Maria De Villota is their test driver but is not due to try out the car for the first time until later in the year.
(Reporting by Mark Elkington, editing by Alan Baldwin)