A part of motorsport's fabled "Triple Crown", the race is one of the biggest in the world and Fernando Alonso's pursuit of the feat took him to IndyCar in search of a win.
His hair was jet black and his shirt starched white when Roger Penske rolled into Indianapolis Motor Speedway for the first time as a team owner, with Mark Donohue behind the wheel.
A five-car pile up with 23 laps to run, triggered when Graham Rahal and Sebastien Bourdais came together, brought out a red flag that set up a mad dash to finish with Pagenaud and Rossi swapping the lead over the final laps.
Simon Pagenaud led this year's Indy 500 from the off in overcast conditions at the Indianapolis Motor Speedway while Colin Herta was an early retirement due to gearbox issues.
If only it were race day.
For Penske, it was his record 18 win in the 500 and second consecutive sweep in May at Indianapolis.
"I've said it before, we build our brand around the country with success at Indy", Penske said.
Rossi lost his cool several times in the race, but the Californian had better fuel mileage than Pagenaud and the Penske cars.
"Horsepower", Rossi said. "That's unfortunately the way it is".
"I mean 2017 with Takuma was really tough; I did everything I could but he did a really great job". And once he finally made his way to victory lane, Pagenaud climbed from his vehicle and let out a primal scream, then dumped the entire bottle of milk over his head.
"We have the best auto, but at the end of the day there is a lot that can happen", Pagenaud said. "Trying to figure out what I need, '" Mears said, expecting some sage advice.
The defending series champion led 110 of 200 laps to win for the second time in the last three races. "The milk motivated me". "Just focus on the job, man".
On the other hand, James Hinchcliffe, who opened at 14-1 in Las Vegas, struggled mightily in qualifying and needed a good lap in last weekend's Las Row Shootout to earn a spot in the 2019 Indy 500 field.
Pagenaud also held off 2017 victor Takuma Sato of Japan before passing Rossi on turn three of lap 199 to become the first driver to win from pole since Penske team-mate Helio Castroneves in 2009. He's one of our drivers. The American leaned in for a genuine embrace despite his disappointment. "This one will be hard to get over".
Pagenaud, the polesitter steered clear of trouble on the track and in the pits, then outraced Alexander Rossi to the checkered flag. Michael has now taken five wins as a team owner. As Rossi finally raced by, he angrily raised his fist at the Spaniard.
"Hopefully I don't have to think this year about being a close call and just make it happen".
"And that's because I know that the last third of the race is the only thing that matters".
Pagenaud got him on the restart and the two went back and forth four more times before Pagenaud locked down the win. Santino Ferrucci in seventh was the highest finishing rookie.