Team Penske teammates Will Power and Helio Castroneves led the opening round of practice at Barber Motorsports Park, concluded just before rain was scheduled to hit the facility. Lightning later hit the track nearing 2 p.m. local time.

Power clocked in at 1:11.2886 ahead of Castroneves at 1:11.5010 around the 2.3-mile road course, as their Chevrolets were among two of the five in the top seven.

Some relative outsiders were next, Takuma Sato and rookie Josef Newgarden third and fourth in their two Honda-powered cars for Rahal Letterman Lanigan Racing and Sarah Fisher Hartman Racing, respectively.

“We're in the ballpark,” said Newgarden, who reckoned there was more speed to be found. “We just need to keep it up, as we can't be quick only at the beginning.

“We worked a bit on the rear,” he added. “The track's better than expected. I thought we'd be out to lunch with the Grand-Am rubber down. We need to find a compromise to try to help the front end understeer.”

Rubens Barrichello showed the first signs of potential IndyCar success with fifth, ahead of fellow Chevy runners Marco Andretti and Tony Kanaan. Simon Pagenaud, Dario Franchitti and Graham Rahal, all in Hondas, completed the top 10.

Sebastien Bourdais led the Lotus runners, a more-than-respectable 16th and only 1.1932 seconds off Power's pace. Dragon Racing teammate Katherine Legge struggled, nearly four seconds off Bourdais at the rear of the field.

Justin Wilson also had a fraught morning, with engine issues either related to the engine itself or the turbocharger after just three laps. The Englishman hopes to be out later Friday, but it may be Saturday before the Dale Coyne Racing No. 18 DW12-Honda returns to the circuit.

Pos  Driver               Team/Car                      Time        Gap
 1.  Will Power           Penske DW12-Chevrolet         1m11.2886s
 2.  Helio Castroneves    Penske DW12-Chevrolet         1m11.5010s  + 0.2124s
 3.  Takuma Sato          Rahal DW12-Honda              1m11.5608s  + 0.2722s
 4.  Josef Newgarden      Fisher DW12-Honda             1m11.5884s  + 0.2998s
 5.  Rubens Barrichello   KV DW12-Chevrolet             1m11.6028s  + 0.3142s
 6.  Marco Andretti       Andretti DW12-Chevrolet       1m11.6263s  + 0.3377s
 7.  Tony Kanaan          KV DW12-Chevrolet             1m11.6800s  + 0.3914s
 8.  Simon Pagenaud       Schmidt DW12-Honda            1m11.7015s  + 0.4129s
 9.  Dario Franchitti     Ganassi DW12-Honda            1m11.7415s  + 0.4529s
10.  Graham Rahal         Ganassi DW12-Honda            1m11.9529s  + 0.6643s
11.  James Hinchcliffe    Andretti DW12-Chevrolet       1m12.0320s  + 0.7434s
12.  JR Hildebrand        Panther DW12-Chevrolet        1m12.0564s  + 0.7678s
13.  Scott Dixon          Ganassi DW12-Honda            1m12.0826s  + 0.7940s
14.  Mike Conway          Foyt DW12-Honda               1m12.1934s  + 0.9048s
15.  Ryan Briscoe         Penske DW12-Chevrolet         1m12.2151s  + 0.9265s
16.  Sebastien Bourdais   Dragon DW12-Lotus             1m12.4818s  + 1.1932s
17.  James Jakes          Coyne DW12-Honda              1m12.5018s  + 1.2132s
18.  EJ Viso              KV DW12-Chevrolet             1m12.5042s  + 1.2156s
19.  Ryan Hunter-Reay     Andretti DW12-Chevrolet       1m12.6237s  + 1.3351s
20.  Simona de Silvestro  HVM DW12-Lotus                1m12.7388s  + 1.4502s
21.  Charlie Kimball      Ganassi DW12-Honda            1m13.0897s  + 1.8011s
22.  Alex Tagliani        BHA DW12-Lotus                1m13.4746s  + 2.1860s
23.  Oriol Servia         Dreyer & Reinbold DW12-Lotus  1m13.4960s  + 2.2074s
24.  Justin Wilson        Coyne DW12-Honda              1m13.9034s  + 2.6148s
25.  Ed Carpenter         Carpenter DW12-Chevrolet      1m14.5717s  + 3.2831s
26.  Katherine Legge      Dragon DW12-Lotus             1m16.3147s  + 5.0261s