Scott Dixon and Scott McLaughlin have set the outright and non-tow pace respectively on an incident-filled opening day of Indianapolis 500 testing.

That was the case in both the morning session for veterans and the latter, all-in hit-out which was brought to a premature end after a Will Power spin triggered a crash for Colton Herta.

Dixon wheeled the #9 Chip Ganassi Racing entry to an average speed of 227.187mph (365.622km/h) on his ninth lap in the third and final session of the day, the Honda driver edging out Chevrolet steerers Conor Daly (Ed Carpenter Racing), Callum Ilott (Juncos Hollinger Racing), and Santino Ferrucci (Dreyer & Reinbold Racing).

McLaughlin was only 17th-fastest in that session, albeit fastest of the Chevrolet-powered, Team Penske trio.

Furthermore, the New Zealander set the benchmark non-tow speed of 219.841mph (353.780km/h), just quicker than Simon Pagenaud’s 219.767mph (353.681km/h) in one of the Meyer Shank Racing Hondas.

The other MSR car, of Helio Castroneves, did not get through the day unscathed after the four-time race winner was one of three to spin exiting the pits.

After a delayed start due to rain, Alexander Rossi looped the #27 Andretti Autosport entry in the veteran session, with little consequences.

Castroneves on the other hand, rotated in such a fashion during the third session that he crunched the outside wall at Turn 1, in the car in which he took victory in the 500 last year.

“I didn’t feel anything strange, anything bottoming, I wasn’t pushing,” said the Brazilian.

“And the rear just spun out. I was trying to control it, making sure I didn’t crash, and it was a very odd situation.

“Unfortunately, we couldn’t avoid that. It was very unusual.”

Power swapped ends in somewhat similar fashion later in the afternoon and while the Penske driver managed to avoid sliding up the oval, Herta’s evasive action caused him to lose control.

His #26 Andretti Autosport car swiped the outside wall with its rear attenuator before spinning down the track.

Herta eventually came to rest without further damage, thanks in part to the reflexes of Marcus Ericsson (CGR).

It was after that incident that the day was called 30 minutes early, due to questions over the track surface, to which a new layer of sealant has recently been applied.

Jimmie Johnson and Romain Grosjean had already passed their rookie orientation in a previous test, while Kyle Kirkwood, Devlin DeFrancesco, David Malukas, Christian Lundgaard, and Ilott did so today.

Marco Andretti completed his refresher test, while two-time race winner Juan Pablo Montoya and Sage Karam are set to do so tomorrow, when testing resumes at 00:00 AEST.

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Results: Test Session 2

Note: Third session of day designated officially as ‘Test Session 2’, after Test Session 1 and ROP Test Session 1