Power was involved in a horror crash during the IndyCar Series practice for the Sonoma Grand Prix in California on Saturday.
His car ploughed into the side of the damaged car of Nelson Philippe.
The pair was airlifted to Santa Rosa Memorial Hospital in San Francisco where early reports suggested Power had broken two vertebrae in his lower back and sustained a concussion.
Power’s father Bob last night told The Chronicle his son’s injuries were worse than first thought.
“The information we have is still a little vague at the moment,” Mr Power said.
“We do know the injuries were a little worse than what they first thought and they have found more fractures in his back.
“From what we’ve been told they are waiting to make a decision on if or when they will operate on him.”
Bob Power said his son was conscious and moving his arms and legs.
“He’s pretty heavily drugged, but he is conscious. It’s just a waiting game at the moment.”
Power’s mother Marg was last night preparing to head to the United States to be with her son.
“Marg is organising herself to head over straight away. Will has been asking for her,” Mr Power said.
“She is a nurse so I think she will be the most helpful one to head over now.”
Power crashed into Philippe coming out of a blind corner at Infineon Raceway.
Philippe lost control at the top of the hill on Turn 3A, and the front end of his car was initially clipped by Dan Wheldon.
Power arrived moments later and couldn’t avoid an ugly crash, T-boning Philippe’s car.
Philippe has reportedly undergone surgery on his foot and he also sustained a concussion in the crash.
This was a big blow — and scare — for Power, who earned his first IndyCar win on July 26 at Edmonton after starting from the pole and leading 90 of 95 laps.
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