Shoya Tomizawa, who won the first ever Moto2 Grand Prix at Qatar this year, died in hospital due to injuries sustained when the 19-year-old fell from fourth place in Sunday's race and was hit at high speed by following riders.
Tomizawa death, the first in motorcycle grand prix since Daijiro Kato in 2003, was announced immediately after the finish of the following MotoGP race.
The following tributes have been paid to Tomizawa (updated regularly)...
(Misano MotoGP winner)
"There are no words to say how it feels after this victory - it feels like nothing. I arrived at parc fermé very happy with the win and I immediately felt that the atmosphere among my mechanics was really strange, everybody was serious. Still with my helmet on they told me about Tomizawa and I couldn't react. It was a big shock, a big contrast for me. I asked three times if it was true because I couldn't believe it. It's so sad, terrible, and these things should never happen.
"As a person I can only say that he was a very funny boy, always happy and making jokes, and as a rider he earned respect from everybody in a very short time, he was fast and brave. To lose two riders in a week is terrible [13-year-old Peter Lenz died in a support race at Indianapolis last Sunday].
"I believe everybody in the World Championship is feeling the same now and I want to send my condolences to the family. When you are born, life gives you the chance to choose what you want to do. Tomi chose to be a rider and in fact he was doing great. I just want to think that he's been happy making his dream come true."
"“My thoughts are with Shoya Tomizawa. I was informed after the race and the news is like a slap in the face. Two tragic accidents in two races is so terrible and it reminds us how dangerous is our job. The safety commission has improved safety levels so much that we often forget this aspect.
"I'm so sorry for Tomizawa's family. Having become a father I can understand that this is the worst thing that can happen for a family. Unfortunately we couldn't do anything: these were two casualties, two accidents with a similar dynamic where the track-side barriers were not touched. This can happen and this is why our job is so risky."
"It's a huge pity because Shoya was a good guy and a strong rider. I am so sad and I just want to say how sorry I am for his family and his friends. When this happens nothing else matters."
"I'm so sorry for Shoya because he was a strong rider but above all he was very 'sympatico.' He was very funny, always smiling and he always had nice things to say to everyone. He was also very young with a great career ahead of him so we are all very sad."