The 24-year-old biker died of chest, head and neck injuries after he lost control of his Honda and collided with fellow Italian Valentino Rossi just four minutes into the race in Sepang on Sunday (23Oct11).
The race was abandoned following the tragedy, which came on the same day as U.S. IndyCar driver Dan Wheldon's funeral. Wheldon died after his car was flipped into the air during a 15-vehicle Indy 300 pile-up in Las Vegas last Sunday (16Oct11).
Paying their respects to flamboyant Simoncelli, British Formula One driver Jenson Button took to Twitter.com and posted, "R.I.P Marco... Such an exciting talent lost. My thoughts are with his family, friends and everyone involved in MotoGP. Motorsport can be so cruel..."
And Button's Formula One teammate Lewis Hamilton writes, "My thoughts are with his family, friends and team at this extremely sad time. Another tragic loss at such an early age."
Meanwhile, rocker Slash also remembered the racer on Twitter.com, writing, "Is it true Marco Simoncelli died?" and then adding, "That's really sad news to hear. RIP Marcos, u were a great rider."