The defending Indianapolis 500 winner nailed a flying lap of 228.811 mph around the 2.5-mile superspeedway in the opening two hours of the day.
Kyle Larson, the 2021 NASCAR Cup Series champion, delivered a thrilling run of his own after putting his #17 Arrow McLaren Chevrolet second on the timesheets at 226.384 mph.
Larson is preparing for his first IndyCar start as part of the ‘Memorial Day Double’ that also includes running NASCAR’s 600-mile race at Charlotte Motor Speedway later that same day on 26 May.
Scott Dixon was third at 226.346 mph, the six-time IndyCar champion and 2008 Indy 500 winner leading the Chip Ganassi Racing Honda contingent ahead of reigning series champion Alex Palou in fourth. Last year’s Indy 500 pole-sitter nailed a best lap of 226.201 mph.
There was only light running in the afternoon before the rain came, but it was enough time for Andretti Global’s Colton Herta to hit a 225.907 mph lap to end up fifth overall – first in the afternoon out of the 21 drivers that recorded a competitive time.
Scott McLaughlin (Penske), Ed Carpenter (Ed Carpenter Racing), Kyle Kirkwood (Andretti), rookie Christian Rasmussen (ECR) and Felix Rosenqvist (Meyer Shank Racing) rounded out the top 10.
There were no incidents on the day, with the only stoppage happening due to track inspections or moisture.
Each of the six drivers running the separate Rookie Orientation Programme and Refresher session were able to complete the three phases.
Of them, Marco Andretti went quickest and ended the day 17th overall. He turned 49 laps, with a best of 222.734 mph.
One day after she was announced in the #51 Dale Coyne Racing with Rick Ware Racing Honda, Katherine Legge was second among the six at 220.664 mph.
Pietro Fittipaldi (Rahal Letterman Lanigan Racing) was third among the group in the ROP session followed by Rasmussen before his late blast up the times, Nolan Siegal (DCR) and Kyffin Simpson (Ganassi).
By the end of the day, Rasmussen and Simpson logged the most laps with 80 each.
Dreyer & Reinbold Racing’s Ryan Hunter-Reay ran the fewest laps with seven, ending up 34th with a best of 206.290 mph.
Callum Ilott, substituting for the injured David Malukas at Arrow McLaren, was the only other driver to stay in the single digits with only eight laps completed. He ended up 27th overall at 221.085 mph.