British Honda driver Jenson Button has suffered a back complaint in practice ahead of this weekend's British Grand Prix.
Button injured his back in a crash with Brazilian teammate Rubens Barrichello last month in Indianapolis and experienced a worrying recurrence in Friday morning's free practice session at Silverstone.
Button took no further part in Friday practice but Honda remain optimistic that he will be fit enough to take part in qualifying on Saturday in front of his home fans.
A team spokeswoman said, "He (Button) is experiencing the same twinge in his back that he experienced as a result of the first corner incident at Indianapolis."
"As a precaution Jenson will rest this (Friday) afternoon. At this point there is no reason to suggest he won't be back in the car on Saturday."
Honda may now use their 23-year-old Austrian test-driver Christian Klien to replace Button in practice.