Colin Edwards will miss the final MotoGP race of the season in Valencia as he awaits surgery on a broken arm.
Edwards, 37, was injured in the accident in which Marco Simoncelli was killed in Sepang last weekend.
He returned to Houston, Texas for checks which showed multiple fractures to his left humerus (upper arm).
The American rider said: "I wanted to be in Valencia next week to give my support to MotoGP but it is not going to be possible."
Fellow American Josh Hayes will stand in as a replacement rider to partner Cal Crutchlow in Spain next weekend.
The 36-year-old double American Superbike champion was due to take part in a test for the Tech 3 team after the race and will now line up in Edwards' place as a one-off.
As well as a broken arm, he suffered cartilage damage and severe bruising and swelling to both wrists and right heel when he struck the prone Simoncelli. He will be out of action for around four weeks.
"Firstly, I want to thank everybody for all their messages of support since Sunday," Edwards said.
"The support and love has been overwhelming and it has been a great comfort to me at this difficult time.
"My heart goes out to the family and friends of Marco and I will miss him a lot, as will the entire MotoGP family. I watched Marco's funeral yesterday and I really wish I could have been there.
"I wanted to go but unfortunately my injuries meant I was unable to travel.
"I know Valentino Rossi spoke to Marco's family on my behalf and I thank him for that. It was a great service and a fitting celebration of his life."