Circuit specialist Scott Dixon continued to set the practice pace at Mid-Ohio, ahead of qualifying for this Sunday’s race.
Ganassi driver Dixon lapped the venue in 1m05.1209s, 0.36s faster than Josef Newgarden.
Newgarden led a tightly-clustered group of Charlie Kimball, Sebastien Bourdais, Ryan Hunter-Reay, Marco Andretti, Juan Pablo Montoya and Will Power.
Hunter-Reay, who won last time out at Iowa, was the top Honda runner in fifth, as Chevrolets locked out the top four positions.
Penske’s Simon Pagenaud was stranded in the pits with an engine issue, and languished at the bottom of the times.