Ryan Briscoe has received a late call-up to join Graham Rahal in an IndyCar test on the Indianapolis road course on Wednesday.
The test is being jointly organised by the speedway and the series to gather information about the track's different configurations as part of the planning process for what is estimated to be a $100 million upgrade program.
These plans could include determining the need for modifications ahead of a possible future IndyCar race on the road layout.
"I thought Sonoma would be the last time I would be driving an IndyCar for some time, so to get the invite to be part of this test is really cool," said Briscoe, who has recently been dovetailing a part-time IndyCar program with Panther with his full-time ALMS commitments with Level 5.
"It's always special to drive at the Indianapolis Motor Speedway - whether it's on the oval or any other course. I'm really looking forward to it."
The only other time an IndyCar has run on the road course at IMS was when Dan Wheldon completed some laps in the clockwise direction during the development phase of the current DW12 chassis, although that test was aimed purely at gathering data about the car.