Nicky Hayden, the World Superbike Championship rider and 2006 MotoGP world champion, has died five days after being involved in a road collision.

The 35-year-old American was cycling along the Rimini coastline in Italy last Wednesday when a car collided with his bicycle.

Hayden, from Owensboro, Kentucky, suffered head and chest injuries in the collision and was transferred to the Maurizio Bufalini Hospital in Cesena, where he was treated in the intensive care unit.

In pictures: Life & times of Nicky Hayden - Moto GP Show all 18 1 /18 In pictures: Life & times of Nicky Hayden - Moto GP In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden Getty Images In pictures: Life & times of Nicky Hayden - Moto GP US Nicky Hayden bursts into tears after winning the 2006 Moto GP championship at the end of season - Valencia Grand Prix Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Italy's Valentino Rossi congratulates US Nicky Hayden after winning the 2006 Moto GP championship Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Ducati new rider Italian Valentino Rossi poses with team mate US Nicky Hayden on 11 January 2011 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Ducati Marlboro Team plays during the pre-event 'Riders will train with the NFL Indy Colts at Lucas Oil Stadium in Indianapolis' of the Red Bull Indianapolis GP at Indianapolis Motor Speedway on August 25, 2011 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Singer Jay Kay, Moto GP rider Nicky Hayden of Ducati and F1 supremo Bernie Ecclestone are seen on the grid before the Italian Formula One Grand Prix at the Autodromo Nazionale di Monza on September 11, 2011 in Monza, Italy Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Ducati Marlboro Team arrives on a scooter in box during the first day of pre season testing of MotoGP at Ricardo Tormo Circuit on November 13, 2012 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Ducati Marlboro Team shows his watch to fans during the pre-event "Riders for Health" during the MotoGp Of Great Britain - 29 August 2013 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Drive M7 Aspar poses and celebrates 200 GP's - 9 April 2015 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Aspar Team MotoGP greets and lifts the front wheel during the MotoGP of Japan - 9 October 2015 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of Aspar MotoGP team poses with a Kangaroo at Maru Koala & Animal Park ahead of the 2015 MotoGP of Australia at Phillip Island Grand Prix Circuit on October 15, 2015 in Phillip Island, Australia Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Aspar Team MotoGP jokes during a pre-event at the Maru Koala Park ahead of the 2015 MotoGP of Australia at Phillip Island Grand Prix Circuit on October 15, 2015 in Phillip Island, Australia Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of USA and Repsol Honda Team smiles during the riders parade before the MotoGP race during the MotoGP of Australia - 23 October 2016 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden of the USA rides the #69 Red Bull Honda World Superbike Team Honda during practice ahead of round one of the FIM World Superbike Championship at Phillip Island Grand Prix Circuit on February 24, 2017 in Phillip Island, Australia Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Nicky Hayden Getty Images In pictures: Life & times of Nicky Hayden - Moto GP Jonas Loris Baz of France and Avintia Racing, Jonas Folger of Germany and Monster Yamaha Tech 3, Marc Marquez of Spain and Repsol Honda Team, Valentino Rossi of Italy and Movistar Yamaha MotoGP, Dani Pedrosa of Spain and Repsol Honda Team and Jorge Lorenzo of Spain and Ducati Team pose with signboard "Thinking on you, Nicky 69" - 18 May 2017 Getty Images In pictures: Life & times of Nicky Hayden - Moto GP R.I.P. Nicky Hayden #69 Getty Images

The Red Bull Honda rider was training in Italy following his 12th-placed finish in the World Superbike Championship race at Imola on 14 May. Members of the rider's family, including his mother Rose and brother Tommy, had flown out from the United States to be beside him during his time in hospital.

His death was announced by the Cesena hospital on Monday afternoon, with doctors explaining that Hayden had suffered “a serious polytrauma” following the accident.

The hospital's statement read: “The medical team has verified the death of the patient Nicholas Patrick Hayden, who has been undergoing care since last Wednesday 17 May in the intensive care unit of the Bufalini Hospital in Cesena following a very serious polytrauma which occurred the same day.”

Hayden upset the odds to claim the 2006 MotoGP championship in one of the most entertaining seasons in recent memory, edging Valentino Rossi to the title to end the Italian's five-year streak of wins



After news of Hayden's accident broke last week, Rossi paid tribute to his competitor and described him as “one of the best friends I've ever had in the paddock”. Dani Pedrosa, Hayden's team-mate in 2006 when he won the world title, posted a photo of the American on his Twitter account, writing: "Always in my heart, champ. RIP Nicky. #69."

The 2006 victory would be Hayden's only championship, but 'The Kentucky Kid' remained in MotoGP until 2015. The following year, he switched to the World Superbike Championship and finished fifth in the overall standings, winning that year's race in Malaysia.