Valentino Rossi has paid tribute to close friend and fellow Italian MotoGP star Marco Simoncelli, who lost his life in an accident involving both riders in Sunday's Malaysian Grand Prix at Sepang.

Simoncelli lowsided from his Gresini Honda while holding fourth place on lap 2 of the grand prix. Simoncelli's bike then regained grip and veered sharply across the track in front of Colin Edwards and Rossi - dragging Simoncelli with it.

Edwards and Rossi could do nothing to avoid hitting the fallen 24-year-old, who suffered 'very serious trauma' to the head, neck and chest.

Edwards sustained a dislocated shoulder, while the impact pushed Rossi off track, before he regained control and returned to the pits.

Visibly shaken, the seven-time MotoGP champion then joined the rest of the paddock in anxiously waiting for further news.

Tragically, Simoncelli's death was announced at 16:56 local time. The race had already been cancelled so that medical staff could concentrate all their efforts on trying to save the former 250cc world champion's life.

In the early hours of Monday morning, Malaysian time, Rossi made his first public comment via his official Twitter account (@ValeYellow46) saying simply:

"Sic for me was like a youngest brother. So strong on track and so sweet in the normal life. I will miss him a lot."