The owner of A.J. Foyt Racing is scheduled to meet with a neurosurgeon in Texas because of the pain.
The 78-year-old Foyt had missed three previous races this season because of sciatic nerve pain in his back. He underwent successful back surgery in Houston in April to relieve the pain and was at the Indianapolis Motor Speedway in time for opening day.
The back problems kept Foyt away from the track for Takuma Sato's win at Long Beach in April. Sato's win was the first for a Foyt driver on a street or road course since Foyt himself in 1978.