Vitor Meira is receiving treatment for fractures of two vertebra in his back at Methodist Hospital in Indianapolis after his massive crash in the Indy 500.
The A.J. Foyt Racing driver tangled with Luczo Dragon's Raphael Matos on the 174th lap, sending Meira nose-first into the wall in Turn 1.
His car then rode up the wall on its side and slid for some distance before coming to a halt. The Brazilian had previously been involved in a dramatic pit fire but continued after having his car doused with water.
An Indy Racing League statement said that Meira "will be treated with non-operative management under the supervision of Dr Terry Trammell and fitted with a back brace."
Matos had been trying to come back through the field when the collision occurred. He had run as high as second, but suddenly dropped out of contention with a 39-second stop when a wheel nut got stuck in an air gun during a stop on lap 134.
"I hope Vitor is OK," Matos said. "It was just an unfortunate incident. We had a good car, and the team had worked so hard. It was just unfortunate to end like that. It's disappointing and frustrating."