Simon Pagenaud ended the second practice session on to of the timesheets, narrowly edging out Chip Ganassi's Felix Rosenqvist.
The gap between the pair read just 0.0603, as all but two drivers set their quickest laps on the Firestone red tyre, after the blacks were used earlier.
Championship challenger Alexander Rossi saw his session fall apart after he made contact with the wall, which damaged his front suspension.
Sebastien Bourdais was third for Dale Coyne ahead of Spencer Pigot and Scott Dixon, who has seen his title challenge take a hit in recent races.
Graham Rahal was sixth ahead of Marco Andretti and the Penske of Josef Newgarden, who enters the weekend still top of the drivers' championship.
Ryan Hunter-Reay was ninth for Andretti while Will Power, who is yet to take a race win this year, rounded out the top ten.
It was a stronger session this time around for Colton Herta, who managed to end the session in 12th behind the Arrow Schmidt Peterson car of James Hinchcliffe.
Hinchcliffe's teammate Marcus Ericsson also hit the wall, but managed to escape without sustaining heavy damage. The Swede finished the session in 22nd place.