Champ Car driver Cristiano da Matta is making "slow, steady progress" but remains in a coma in intensive care five days after colliding with a deer.
Da Matta hit a deer while testing at Road America in Elkhart Lake
The 32-year-old Brazilian had swelling around his brain following surgery to remove a ruptured blood vessel in his head, but his condition is improving.
The former Toyota F1 driver hit a deer that ran onto the Road America track in Elkhart Lake, Wisconsin.
Da Matta has 12 Champ Car victories and claimed the series title in 2002.
He required emergency surgery to treat a subdural hematoma and was airlifted to the Neenah, Wisconsin, hospital for treatment.
He'll remain in the Intensive Care Unit while his condition and progress are being monitored
Chris Pinderski, the Champ Car director of medical affairs
Chris Pinderski, the Champ Car director of medical affairs, is monitoring Da Matta's condition, in consultation with the attending doctor, Randall R Johnson.
"Cristiano continues to make slow but steady progress while in the Intensive Care Unit at Theda Clark Medical Center," said Dr Pinderski after visiting Da Matta on Monday.
"At this point in his recovery, Dr Johnson has begun to decrease Cristiano's sedation.
"The care Cristiano has been receiving has been excellent and he'll remain in the Intensive Care Unit while his condition and progress are being monitored."
Dr Pinderski reported on Saturday that repeat CT scans showed no further bleeding, but that Da Matta had "some cerebral edema, which is swelling of the brain itself".
"This is common with significant head injuries and was expected in this situation," he added.
Da Matta competed in 28 grands prix for Toyota in 2003 and 2004, scoring 13 points.
The Toyota team issued a statement at the weekend.
It said: "When he was with Toyota, Cristiano was always a fighter and everyone involved in the team wishes him the best as he fights for his recovery."
Da Matta's RuSport team withdrew his team-mate, Yorkshireman Justin Wilson, from the remainder of the testing session.