Alex Zanardi's condition remained stable in hospital on Sunday, a 'positive' sign for doctors two days after the former Formula One driver turned Paralympic champion suffered serious head injuries in a handbike crash in Italy.
"The positive thing is that the more time passes and conditions remain stable, this gives us hope," Dr Sabino Scolletta, head of critical care at the Santa Maria delle Scotte hospital in Siena, told journalists.
"It means that there has been no step backwards and this gives us great confidence."
Zanardi suffered serious head injuries with multiple facial factures and fears for his sight after losing control of his bike and colliding with a truck during a race in Italy on Friday.
The 53-year-old Italian was airlifted to hospital in Siena and underwent three hours of delicate neurosurgery before being placed in an artificial coma and on a ventilator.
"We cannot rule out complications," Dr Scolletta told journalists.
"Compared to when Alex Zanardi arrived in the emergency room, conditions have really changed," the doctor said.
"We hope that the clinical condition remains stable, which would give us the opportunity during the week to start assessing the neurological situation."
An investigation has begun into the circumstances surrounding the accident in Tuscany and the truck driver has already been questioned.
Investigators have seized the truck and Zanardi's handbike and mobile telephone.
A former Formula 1 driver, Zanardi has become one of the great figures in disabled sports after both his legs were amputated in 2001 following a motor racing accident on the Lausitzring track in Germany.
He went on to win four gold medals on his handbike in the 2012 and 2016 Paralympic Games, and two silver medals, and multiple world titles.
"He is a great athlete and we hope that this will also apply in this demanding situation," added Dr Scolletta.
Zanardi raced for Jordan, Minardi and Lotus in Formula 1 in the early 1990s before switching to the CART championship in the United States where he was series champion in 1997 and 1998.
He returned to F1 with Williams in 1999 before heading back to CART.
His passion remained motor racing and he had recently announced he would drive a specially-adapted BMW in the final endurance round of this year's Italian GT Championship at Monza in November.
Alex Zanardi competing in the Rome Marathon in April 2017.