Australia's Blake 'Bilko' Williams has withdrawn from Moto X Best Trick and Freestyle for X Games 16. The defending freestyle champion and silver medalist in Best Trick, Williams broke his collarbone in late June when he failed to stomp a cliffhanger backflip in the third round of the Red Bull X-Fighters in Moscow.

Williams rushed back to the U.S. to have the collarbone surgically repaired with a plate and began an intense rehab program with the hopes of being prepared for X16. But he aggravated the injury while hitting smaller, warm-up jumps Thursday and cannot compete.

"I was just cruising around, and my bars got a slight bit of head shake -- not even enough to make me go sideways -- and that gave my arm a gentle tug. I felt a harsh tearing sound and grinding feeling followed by immediate weakness and pain," Williams told ESPN FMX.

An MRI revealed that he had torn his labrum and ripped out one of the sutures used to repair the collarbone.

Williams expressed disappointment over the new injury but recognized that it was a far better situation to have sustained it while warming up as opposed to during X Games itself. "If I had hit a ramp, it would only be a matter of time before the strain of doing tricks would have finished it off, and I could have very well been hanging off my bike when it did tear, with no chance of getting back on. That could have ended in more severe injuries."

As has been the case in the past, Williams was unwilling to let the setback get him down: "I will be back next year to claim back what I believe is mine … another X Games gold medal!"