Will Power topped a disrupted Practice 2 session ahead of the championship leader Alex Palou.
Colton Herta set the third quickest time as Simon Pagenaud suffered a hefty shunt but walked away and used the spare Meyer Shank Racing car later in the session.
At the green light, a flurry of cars rolled onto the circuit at Mid-Ohio for the second Practice session ahead of the Honda Indy 200.
Arrow McLaren SP’s Pato O’Ward topped the timesheets early on with a 1:13.9910 ahead of Argentinian driver Agustin Canapino.
The 19 drivers on-track used the harder Firestone Primary tyre within the first five minutes.
Power became the first driver to break the 1:10 barrier, setting a 1:09.6476 before the Team Penske driver was usurped by a multitude of the gird, including Herta. The American achieved a 1:07.7772 for Andretti Autosport.
Kyle Kirkwood sat in second place in an Andretti 1-2, ahead of New Zealander Marcus Armstrong on his first visit to Mid-Ohio.
The red flags were brought out with 28 minutes to go in the 45-minute session as Pagenaud crashed and came to a stop upside down against the tyre barrier at Turn 4 in a highly dramatic crash.
The AMR Safety Team acted swiftly, and the Frenchman walked away from his number 60 Meyer Shank Racing car.
After a 13 minute delay, the session restarted, and Josef Newgarden went to the top of the timesheets with a 1:07.3353 ahead of Alexander Rossi as the times continued to tumble.
Scott Dixon spun at Turn 6 with half an hour to go for Chip Ganassi but managed to restart his number six car and continue with his run.
In a competitive session, Graham Rahal improved and set the quickest time for Rahal Letterman Lanigan at his home race.
O’Ward soon bested Rahal’s effort, setting a 1:06.7947; Dixon became his closest challenger 20 minutes into Practice 2.
Herta retook the top spot going two tenths quicker than the McLaren driver with 18 minutes to go.
The times continued to tumble as Power set the quickest time, driving to a 1:06.4905 ahead of the championship leader Palou, before diving into the pit lane.
The red flags were brought out again with 15 minutes left as Santino Ferrucci crashed at The Carousel.
The incident was cleared, the session got restarted with Power holding the fastest time. Marcus Ericsson toiled down in P23 for Chip Ganassi, just behind British driver Callum Ilott.
