Scott Dixon has ended the first practice session of the weekend at Mid-Ohio on top of the timesheets, beating Spencer Pigot by just over a tenth of a second.
Dixon has started the weekend strongly on the back of an impressive display at Iowa last weekend, where he finished second behind winner Josef Newgarden.
Dixon's fastest lap of the session was a 1:06.0973, which was good enough for the top spot on the black Firestone tyres.
Simon Pagenaud and Josef Newgarden were third and fourth for Team Penske, meaning Dixon was the only Honda-powered driver inside top four.
However, much of the rest of the top ten was made up of Honda cars, as James Hinchcliffe and Ryan Hunter-Reay were fifth and sixth respectively.
Will Power was seventh in the third Penske car, ahead of Felix Rosenqvist, who is sporting a new green and white livery for the weekend.
Sebastian Bourdais was ninth, leading Max Chilton and Jack Harvey, with the latter making his first start since the round at Road America.
Colton Herta had a scary off-track moment during the session but managed to keep it together and end the session in 12th, ahead of two Indianapolis 500 winners - Alexander Rossi and Takuma Sato.
RC Enerson, who is making his first appearance of the year, concluded the session in 21st, ahead of Zach Veach and Tony Kanaan, who rounded out the timesheets.