Spain's Oriol Servia notched the fastest practice time on Thursday among the 10 drivers who took the track to prepare for qualifying bids this weekend for the Indianapolis 500.

Servia's lap of 356.21km/h was seventh overall in the practice session on the fabled 4.0km Indianapolis Motor Speedway oval, where the the Indianapolis 500 will be held on 24 May.

Most of the 22 drivers in action on Thursday had already qualified for the race, but Servia was among those hoping to book a place in the 33-car field in qualifying sessions on Saturday and Sunday.

Servia was 11th as a rookie last year, but missed the first three IndyCar series events this season as the Rahal Letterman team scrambled for sponsorship.

"People keep asking me if I felt any pressure getting such a late start," Servia said. "But the truth is this is the first day I've felt relief in five months."

Townsend Bell was second-quickest among non-qualified drivers with a lap of 220.93. Bell is vying to join two teammates already in the field: Brazilian Mario Moraes and Canadian Paul Tracy.

Moraes had the fastest time of the day at 356.37km/h.

Another six-hour practice session was scheduled for Friday. The final 11 spots on the starting grid will be up for grabs on Saturday, and any remaining hopefuls can try to bump the slowest qualifiers from the field on Sunday.

Rookie Robert Doornbos of the Netherlands was back on the track for the first time since crashing last Saturday.

English rookie Mike Conway, who spent Saturday night in hospital with bruised lungs and a mild concussion after a crash, was to be examined by speedway doctors on Friday morning to determine if he could resume driving and try to qualify.

"I'm feeling OK now," said Conway (25). "I was sore on Tuesday, but I feel ready to get back into the car."