Nicky Hayden
2006 MotoGP world champion Nicky Hayden suffered serious head injury and remains critical after a cycling accident in Italy on Wednesday (17 May)Reuters

Former MotoGP world champion Nicky Hayden remains in an extremely critical condition after suffering serious cerebral damage following a cycling accident in Italy on Wednesday (17 May).

The American rider, who currently races in the World Suberbike Series, was cycling along the Rimini coastline when he collided with a car and suffered serious head and chest injuries and has reportedly been place in an induced coma at the Bufalini hospital in Cesena.

"The young man, who is still in the intensive care unit of Cesena's Bufalini hospital, has suffered a serious polytrauma with subsequent serious cerebral damage," a hospital statement read, as quoted by the BBC.

"The prognosis remains reserved."

Hayden popularly known as the 'Kentucky Kid' won the MotoGP world championship in 2006 with the Repsol Honda team denying Valentino Rossi a sixth consecutive title. He spent a further nine years in MotoGP racing with Ducati and the Aspar team before making a switch to the Superbike series and currently rides for the Red Bull Honda World Suberbike Team.

The 35-year-old took part in the Italian round of the SBK series last Sunday (14 May) and was spending time in the country ahead of the next round at Donington Park in the United Kingdom on 28 May. Hayden's family and team are currently by his bed side, and the entire motorsport world has rallied behind the American praying for his quick recovery.

"Nicky is one of the best friends I've ever had in the paddock," nine-time world champion Valentino Rossi wrote on his Instagram page.

"The most beautiful thing I have about him is when he gave his hand to me after the unlucky race of Valencia 2015, on the lap of honour. For him it was his farewell to MotoGP, I had just lost the world [title]. [The] supporting look inside his helmet is one of the few positive memories I have of that day. For Nicky, we're all with you," the Italian MotoGP legend added.

Below are tweets from his former teammate Casey Stoner, reigning world champion Marc Marquez, Ducati rider Jorge Lorenzo and others praying for the American rider's quick recovery.