Fernando Alonso could spend a second night in hospital, his manager Luis Garcia Abad has admitted.
The Spaniard is currently in a Barcelona hospital after a mysterious crash during the final day of the second 2015 winter test.
The cause of the crash has not been revealed by McLaren, triggering wild theories, including that he received an electric shock from Honda’s troublesome KERS or he inhaled toxic fumes from a malfunctioning battery.
As for Alonso’s condition, the 33-year-old was reported to have been initially unconscious, and then taken first by ambulance to the circuit medical centre, and later to a nearby hospital for what McLaren called "precautionary" checks.
Jordi Vidal, a trackside photographer, is quoted by Spain’s AS newspaper: "Doctors tapped him on the helmet but he did not react. This lasted for about ten minutes."
Vidal captured images of Alonso sliding down the wall with the right side of his MP4-30 at a fairly low speed.
According to Spanish radio Cadena SER, the newspaper cited sources at the General Hospital de Catalunya who said Alonso arrived conscious and talking to doctors.
"We have the result of the CT scan and Alonso is uninjured and fine," a McLaren spokesman confirmed.
Team boss Eric Boullier added: "Fortunately he’s fine, but he was concussed during the accident, which therefore required an overnight stay in hospital as a precaution."
The Frenchman also played down some of the wilder circulating rumours about the cause of the crash, with multiple sources confirming that although the crash may not have appeared overly heavy, it did trigger the FIA’s 15G impact light.
Other reports, including the Spanish broadcaster Antena 3, indicated on-board data of up to a hefty 30G impact.
According to Italy’s Autosprint, Alonso’s trainer and assistant Fabrizio Borra admitted the driver had been "agitated" after the crash, causing medical staff to administer sedatives for his trip to hospital.
Alonso’s manager Luis Garcia Abad, meanwhile, told Spanish language reporters in Barcelona that claims the driver was unwell when he stepped into the car are not true.
"The hit with the wall caused everything," he insisted.
"He is comfortable and calm, and it was a completely normal situation.
"He is going to be observed in hospital for 24 to 48 hours," he added.
"The important thing is that Fernando has always been conscious."
Asked if Alonso could miss the forthcoming Barcelona test, or the season opener in Melbourne, Abad insisted: "He’s ok, I do not think there will be any problems.
"He’s fine."