The two-time Formula One world champion is preparing for his eagerly-awaited return to the F1 grid with Alpine next month, having been out of the sport for the last two seasons.
But his participation in pre-season testing – which takes place in Bahrain on March 12/14 – as well as the season-opening race at the same track two weeks later is now in huge doubt.
Reports emerged that the Spanish star, 39, had been hit by a car while cycling near his home in Lugano – and his F1 team confirmed on Thursday evening that Alonso is “conscious and well in himself”.
It has also been speculated that Alonso has suffered a broken jaw, although Alpine remained tight-lipped on his condition and said they will provide a further update on Friday.
Alpine, formerly known as Renault and renamed after the French manufacturer’s sportscar brand, said: “Alpine F1 Team can confirm that Fernando Alonso has been involved in a road accident while cycling in Switzerland.
“Fernando is conscious and well in himself and is awaiting further medical examinations tomorrow morning.
“Alpine F1 Team will not make any further statement at this point in time. Further updates will be given tomorrow.”
According to Italian publication La Gazzetta, the Spaniard – who won back-to-back F1 world titles with Renault in 2005/06 – was riding his bicycle in Switzerland when he was hit by a car.
The outlet also claims that Alonso may have suffered a possible fractured jaw, an injury which would put his place on the grid for next month’s season-opener in jeopardy.
Alonso, who turns 40 in July, has been out of the sport since he appeared to bring down the curtain on his career with McLaren at the end of the 2018 season.
But the Spaniard, who won successive championships with Renault, has completed a sensational comeback with the French manufacturer, who have been rebranded as Alpine.
Alonso has competed in 311 grands prix, winning 32 of them. He starred for Renault in the early years, before quitting McLaren after one season following a turbulent campaign alongside the then-rookie Lewis Hamilton
He returned to Renault before a four-year period at Ferrari where he came close to winning the title on two occasions.
After falling out with the Italian team, he went back to McLaren, but the switch proved desperately unsuccessful.
Alonso quit the sport after four seasons with McLaren but will now return to partner Esteban Ocon at Alpine this season.