Former Formula 1 driver Alex Zanardi remains in a serious but stable condition after an accident during a handbike relay in his native Italy.
The 53-year-old Paralympian suffered head injuries in a crash with a lorry in Pienza on Friday.
Zanardi had surgery at a hospital in Siena, where he remains on a ventilator in intensive care.
The hospital said his "neurological picture remains serious" and his organ functions are "adequate".
Zanardi had both legs amputated after crashing in the American Memorial 500 Cart race at Lausitz, Germany, in 2001.
He has since become a four-time Paralympic handcycling gold medallist.
Speaking on Saturday, Zanardi's surgeon said: "The operation went as it should have; it was the original situation that was not good.
"What the prognosis will be tomorrow, in a week, in 15 days, I don't know.
"Serious means he's in a situation where he could die, in these cases improvements can be very small over time and worsening can be sudden."
Zanardi was taking part in an event called the Obiettivo Tricolore, a journey where the participants ride across Italy on handbikes, cycles or wheelchairs.