Austin Butler, Madelyn Cline, Dylan Sprouse lead the star-studded guest list at the 108th Indianapolis 500 amid severe rain delays

Austin Butler led the star-studded guest list at the 108th running of the Indianapolis 500 on Sunday. 

The Oscar nominee was joined by his Bikeriders co-star, Jodie Comer, with whom he's set to wave the green flag to signal the start of the race.

The British actress joked that she watched a YouTube video of fellow actor Adam Driver waving the flag at the Indianapolis Motor Speedway last year in preparation. 

'Maybe I should have practiced,' Butler chimed in during an interview with WTHR-TV.

Dylan Sprouse was also spotted at the track with his wife, former Victoria's Secret model Barbara Palvin. 

Austin Butler was spotted at the Indianapolis Motor Speedway ahead of the Indy 500

Former child star Dylan Sprouse also attended with his supermodel wife, Barbara Palvin

The Disney Channel alum, who will serve as grand marshal of the famed annual race, is set to give the traditional command for drivers to report to their cars during the pre-race ceremonies.

Other stars spotted at the Brickyard included YouTuber Lilly Singh, Anyone But You actor Darren Barnet, rapper Flavor Flav and Outer Banks star Madelyn Cline. 

Longtime talk show host David Letterman, who is a co-owner of the Rahal Letterman Lanigan team, was also on hand to support his drivers.

The celebs appeared to be in high spirits despite strong storms sweeping across the Midwest causing a delay to the race start.

Outer Banks actress Madelyn Cline stunned in a crop top and white pants at the evnt

Butler will wave the green flag with his Bikeriders co-star, Jodie Comer

Officials were forced to evacuate about 125,000 fans who had already arrived for 'The Greatest Spectacle in Racing,' with attendees being instructed to shelter in place. 

It remains unclear when the 500-mile race will begin. 

It comes amid one of the biggest days in global motorsport, as Ferrari's Charles Leclerc claimed victory at the Formula 1 Monaco Grand Prix across the Atlantic. 

The Monegasque driver held off McLaren's Oscar Piastri to win his home race for the first time in front of a jubilant crowd. 

Plenty of A-listers were on hand to witness the victory, including Kylian Mbappe, Anya Taylor-Joy, Joe Jonas, Alexandra Daddario, Heidi Klum, Emily Ratajkowski, Nicholas Galitzine and Michael Douglas. 

Darren Barnet, who was spotted at the 2023 Indy 500, headed back to Indiana for the race

Rapper Flavor Flav was also photographed before severe rain delayed the race start

It remains unclear what time the 108th running of the Indianapolis 500 will begin