James Hinchcliffe is in a stable condition after undergoing leg surgery following the latest crash in the build-up to the Indianapolis 500.
Doctors operated on an unspecified injury to his upper left thigh inside the first hour of practice for Sunday's race where he has qualified on the outside of row 8 in 24th.
IndyCar's medical director Dr Michael Olinger confirmed the surgery at the IU Health at Methodist Hospital and said that Hinchcliffe was in a stable condition.
The popular Canadian, who won the second race of the season at New Orleans, lost control of his Schmidt Peterson Honda at Turn 3 with the car making heavy contact with the wall before it slid on its side briefly before coming to rest right-side up.
Indications are that the crash was triggered by the right-front suspension failing.
Carpenter's crash saw IndyCar peel back horsepower and ordered all cars to run in race aero trim for the qualifying run yesterday.
Hinchcliffe's shunt forced practice to be stopped before it resumed quite a while later with Sage Karam ending up fastest from pole winner Scott Dixon with JR Hildebrand third fastest.
Australian James Davison, who will start the race from 21st after seeing Tristan Vautier qualify the machine, continues to impress after finishing fourth fastest in the #19 Dale Coyne entry in the latest round of practice.
A final one hour practice session is scheduled for Friday ahead of Sunday's 200-lap Indy 500.
See video below of the Hinchcliffe accident