Leading figures from the worlds of both motorcycle and car racing have been paying tribute to Marco Simoncelli, who was killed today in MotoGP's Malaysian Grand Prix.
The 24-year-old Italian, who had been the sensation of the 2011 season, fell on lap two of the Sepang race and was struck by following riders. He was pronounced dead at the circuit's medical centre shortly afterwards.
Nicky Hayden, Ducati MotoGP rider
"Sometimes life just don't make sense... RIP #58, you were a star on and off track. We are all going to miss you."
Suzuki MotoGP team
"All at Rizla Suzuki are deeply affected by today's tragic events and send their deepest condolences to Marco's family and friends during this time of great loss."
Mark Webber, Red Bull Formula 1 driver
"RIP Marco. A special talent that will be missed... Thinking of your loved ones, and all the MotoGP paddock."
Chaz Davies, World Supersport champion
"RIP Marco. Our sport has lost a great rider and all round great guy. My thoughts are with his family. I was fortunate enough to be team-mate to Marco in 2002. He was a genuinely fun guy and taught me my first unrepeatable Italian!"
Taka Horio - General Manager, Bridgestone Motorsport Department
"Today we are left devastated. Our thoughts and prayers are with Marco's family at this terrible, terrible time, and with his team. Words can do no justice to the emotion we are all feeling. The MotoGP family has lost one of its bright stars, a genuine character whose larger-than-life persona, charisma and unstoppable spirit were infectious, and we've all lost a great friend. We worked closely with Marco for his first two years in MotoGP and it was clear that he was a true racer, something he proved again and again this season. Determined to the end, and a great showman. His ascent through the field in just two seasons has been fantastic to watch, testament to his raw talent, ability and dedication to the sport he so loved. We remember fondly the tenacity and spirit with which he raced, and he will be sorely, sorely missed."
Malcolm Wilson, Ford World Rally team boss
"Today has obviously been overshadowed by the tragic death of Marco Simoncelli in the MotoGP race in Malaysia. Marco visited M-Sport just a few weeks ago to test a Fiesta RS WRC. His enthusiasm and delight at being in the car were clear for all to see and we are all extremely saddened at the news. Our sincere condolences go out to his family, friends and colleagues."
"MotoGP extends its deepest condolences to Marco's family, friends and team at this tragic loss."
Williams Formula 1 team
"Thoughts with Marco Simoncelli's family and friends today after the MotoGP rider succumbed to his injuries after terrible crash this morning."
Heikki Kovalainen, Lotus Formula 1 driver
"I can't believe MotoGP star Simoncelli has died in a crash, another great talent lost today."
Karun Chandhok, Lotus Formula 1 reserve driver
"What a horrible week for our sport... Just heard Marco Simoncelli has been killed at the MotoGP race today... Huge talent - big loss to MotoGP."
"Devastated and heartbroken. Thank you for all your kind words."
Cal Crutchlow, Tech 3 Yamaha MotoGP rider
"RIP Marco Simoncelli! A great rider and all round nice guy. My thoughts are with all his family and friends. I will never forget today."
Tommy Hill, British Superbike champion
"So, so sad! Absolutely terrible and heartbreaking when this happens in our sport! All my regards to Marco Simoncelli's family and close friends."
Yamaha MotoGP team
"Rest In Peace Sic... our thoughts are with your family and team. A tragedy."
Shuhei Nakamoto. HRC executive vice president
"I just don't know what to say, words escape me. Marco was a very nice guy and a very talented rider. Sometimes I was a little harsh with him, for example after his first MotoGP podium in Brno when I told him: 'Lucky podium!' and he was so angry... but I wanted to motivate him as I knew he was able to do even more. I was thinking that when he won his first race we would have been able to celebrate together... Now I just want to say thank you to Marco, for what you gave me and pass my sincere condolences to his family and this very sad time".
Dani Pedrosa, Honda MotoGP rider
"In a tragedy like this there is not much to say. I just want to give my condolences to his family and all the people who love him. I've been with his father and all we could do was to hug, nothing else matters. It was a fatal accident and everybody in the paddock remains in shock. Many times we ourselves forget how dangerous this sport can be and when you lose people on the way nothing has any meaning. It's clear that we all do what we like, what we love, but on days like today nothing matters."
Andrea Dovizioso, Honda MotoGP rider
"In these circumstances, words don't seem to be appropriate. I think of Marco's family and all the people dear to him, in particular his father and mother. I also have a child and what happened today is the hardest situation you can imagine. I watched the images and I'm shocked: in a race you fight and push hard and disaster is often around the corner. Marco was a strong rider and he always pushed hard. We raced together since we were kids, I saw him always pushing to the maximum, he crashed many times, but without major injuries, he was seemed invincible. What happened today seems impossible."
Casey Stoner, MotoGP world champion and Honda rider
"I'm so shocked and saddened by the loss of Marco. When things like this happen it reminds you how precious life is, it makes me feel sick inside. All I can say is how sorry I am for Marco's whole family I can't imagine what they are all going through and our thoughts and wishes are with them at this time. I hope they all stay close and pull through this tragedy together."
Jenson Button, McLaren Formula 1 driver
"RIP Marco... Such an exciting talent lost. My thoughts are with his family, friends and everyone involved in MotoGP. Sometimes motorsport can be so cruel..."
John Hopkins, Suzuki British Superbike and MotoGP rider
"God Speed #58 Simoncelli... Your fighting spirit will live on forever!"
LCR Honda MotoGP team
"A great tragedy hits the MotoGP world today, we have lost a friend in Marco Simoncelli. We cry for a friend."
Carl Fogarty, four-time World Superbike champion
"Devastated to hear that Marco Simoncelli has died. The guy was a breath of fresh air in MotoGP. Can't believe it."
Jorge Lorenzo, Yamaha MotoGP rider
"I don't know what to say on a day like this... I only know that we will miss you. Rest in peace Marco."
Ducati MotoGP team
"Ducati, its team and its riders are deeply affected by the tragedy that struck the MotoGP world today, and they gather around the family, friends and team of Marco Simoncelli, who lost his life in a terrible accident during the Malaysian Grand Prix. We will always remember Marco for his smile, his enthusiasm, his big heart and for the incredible emotions he allowed us to experience in recent years. He was one of us."
Pramac Ducati MotoGP team
"Ciao Marco. You will always be in our hearts."
Tony Kanaan, KV IndyCar driver
"RIP Marco... Such a talent lost. My thoughts are with his family, friends and everyone in MotoGP."
Carlin, GP2, Formula Renault 3.5 and Formula 3 team
"Another sad day for motorsport. RIP Marco and Dan [Wheldon]. Just too awful."
Fairuz Fauzy, GP2 driver
"Tragic and sad news, #58 Marco Simoncelli has died, RIP Marco. My deepest condolences to his family members."
Jean-Eric Vergne, Toro Rosso Formula 1 reserve driver
"Another really sad day for motorsport."
Lotus Formula 1 team
"We would like to add our deepest condolences to the friends and family of Marco Simonelli after the tragic accident in Sepang. RIP Marco. Marco was a true talent whose light has gone out far too soon on another horrible day for motorsport.
Helio Castroneves, Penske IndyCar driver
"Another [piece of] sad news in racing at the MotoGP. RIP Simoncelli. My thoughts and prayers to his friends and family."
Virgin Formula 1 team
"Our thoughts are with the family, friends and many fans around the world of Marco Simoncelli."
Juan Pablo Montoya, Earnhardt Ganassi NASCAR driver
"RIP Marco Simoncelli. He was such a nice guy. My thoughts and prayers to his family and all his friends."
Yamaha MotoGP team
"Yamaha wish to convey the deepest heartfelt condolences and sympathies to the family, friends and colleagues of Marco Simoncelli following the tragic accident today at the Grand Prix of Malaysia. Marco was a worthy competitor and rising star of MotoGP who will be deeply missed by all."
"Sic was like a younger brother to me. He was as tough on the track as he was sweet in life. I still can't believe it, I'll miss him hugely."
Luca di Montezemolo
"I am very sad to hear of the death of Marco Simoncelli. I was very impressed by his speed, talent and the determination he showed this year. His qualities reminded me of Gilles Villeneuve and now, fate has chosen to link them in this tragic fashion. On behalf of everyone at Ferrari, I offer all our condolences to Marco's family for their loss."
"It's hard to express in words the pain felt at the loss of such a cheery character like Marco Simoncelli. Events such as these and the equally tragic loss of Dan Wheldon a week ago in the Las Vegas Indy Car race, remind us how all those who take part in motor sport are always exposed to these risks. One must never drop one's guard, aware that there is nothing one can do against fate. Now, the thoughts of all of us men and women at Ferrari and those at the Mugello circuit go out to Marco's family and friends and his team. I am really close to Fausto Gresini, a dear friend who comes from my home town, Imola, who is going through a particularly fraught time right now."