Mike Conway was released from hospital in Indianapolis on Monday following his violent crash in practice at the weekend.
The British rookie sustained bruised lungs when he spun his Dreyer & Reinbold car into the wall at the start of the pre-qualifying warm-up session on Sunday morning.
Although he remained awake and alert after the accident, he was kept in Methodist Hospital in Indianapolis overnight for observation.
As Conway also sustained a mild concussion in the impact, the Indy Racing League has ruled that he should sit out this week's practice days, before undergoing medical checks on Saturday to see if he is fit enough to participate in the final weekend of qualifying.
"I'm feeling okay," said Conway. "I just want to thank the safety crew and the IndyCar Series medical staff for recovering me from the car and for taking good care of me. I'm feeling much better and recovering well after one day."
Darren Manning, Conway's team-mate in the opening two rounds, is present at Indianapolis and has been tipped as the most likely substitute should Conway not receive clearance to drive next weekend.
Dreyer & Reinbold still has to get three of its four entries into the Indianapolis 500 as only Davey Hamilton made the cut on the first weekend of qualifying. Milka Duno could not muster enough speed, while John Andretti crashed on a practice run and was subsequently bumped out of the top 22.