Alex Zanardi is to be kept in an induced coma until at least next week after suffering severe head injuries in an accident on his hand cycle.
The 53-year-old, a former Formula 1 driver turned four-time Paralympic gold medallist, collided with a lorry during a race in Pienza, Italy, on Friday.
A statement from the Sienna hospital where the Italian is being treated said he remained in a stable condition.
It said his "neurological condition remains unchanged in its severity".
Zanardi is in intensive care, sedated, intubated and on a ventilator.
The hospital statement said any reductions in his sedation "to assess his neurological condition", will be considered starting next week.
The statement said Zanardi's prognosis was confidential.
Zanardi has become a global sporting icon for the strength of will and determination he has shown in overcoming adversity in his career, after he lost both his legs in an accident while racing in a Champ Car event in Germany in 2001.
Zanardi drove in F1 from 1991-94 and in 1999, for the Jordan, Minardi, Lotus and Williams teams, scoring a best result of sixth place.
He raced in the US-based Champ Car series from 1996-98, winning the title in 1997 and '98.
He returned to Champ Cars in 2001 but the Lausitzring accident ended his career in single-seaters.
After extensive rehabilitation, he returned to motorsport in 2005, spending four years racing for BMW in the World Touring Car Championship, and winning four races.
He then turned to hand-cycling, in which he has won 12 world championships in addition to his four Paralympic gold medals, as well as the New York City marathon in 2011.