Indianapolis 500: Will Power and Penske lead first practice day

The Australian topped the charts with a tow-assisted best average lap speed of 223.057mph, edging out team-mates Juan Pablo Montoya (222.502mph) and Helio Castroneves (222.373mph).

"It's great to be at the top of the speed charts, but the car felt really good too, and we got to do quite a few laps," Power said.

"We were just anticipating that it might be wet the next couple of days. It's only practice, first day, [but it's] always handy to be at the top."

On an afternoon when many cars only opted for brief shakedown runs and 10 of the 33 entries did not run at all, the Penske Dallara-Chevrolets were among the few cars to complete a solid day's worth of running, with the three cars covering a combined 197 laps.

JR Hildebrand was fourth-fastest in his first run out in the second Ed Carpenter car, with Ryan Hunter-Reay ending the day in fifth for Andretti.

NASCAR star Kurt Busch's official preparations began with the Andretti driver going 12th fastest at 220.352mph and embracing the opportunity to understand how the car works in dirty air.

"Our car definitely changed," he said. "The attitude and dirty air... it's exciting because every corner is different. And you have to remember where each of those moments [were] from the lap before; and then continue to gain more information and digest what just happened in the next lap.

"And things are moving quickly at 220, and that was with just a few cars [on the track]. So I know there's going to be more dirty air and there's going to be tougher conditions."

Last year's winner Tony Kanaan competed a dozen laps to finish up 10th-fastest, while Brickyard returnee Jacques Villeneuve ticked off 70 laps on his way to 14th.

Prior to the track being opened for official practice, Sage Karam completed the final phase of his rookie orientation, clearing the way for the Ganassi rookie's participation in the 500.

Pos  Driver              Team/Engine      Speed    Time      Gap       Laps
 1.  Will Power          Penske/Chevy     223.057  40.3485s            82
 2.  Juan Pablo Montoya  Penske/Chevy     222.502  40.4490s  +0.1005s  32
 3.  Helio Castroneves   Penske/Chevy     222.373  40.4726s  +0.1241s  83
 4.  JR Hildebrand       Carpenter/Chevy  222.200  40.5040s  +0.1555s  24
 5.  Ryan Hunter-Reay    Andretti/Honda   222.134  40.5160s  +0.1675s  47
 6.  EJ Viso             Andretti/Honda   222.105  40.5214s  +0.1729s  28
 7.  Charlie Kimball     Ganassi/Chevy    221.845  40.5689s  +0.2204s  12
 8.  Ed Carpenter        Carpenter/Chevy  221.772  40.5822s  +0.2337s  47
 9.  Townsend Bell       KV/Chevy         220.840  40.7534s  +0.4049s  19
10.  Tony Kanaan         Ganassi/Chevy    220.755  40.7691s  +0.4206s  12
11.  Carlos Munoz        Andretti/Honda   220.581  40.8013s  +0.4528s  36
12.  Kurt Busch          Andretti/Honda   220.352  40.8437s  +0.4952s  31
13.  Scott Dixon         Ganassi/Chevy    220.226  40.8671s  +0.5186s  11
14.  Jacques Villeneuve  Schmidt/Honda    220.070  40.8960s  +0.5475s  70
15.  Ryan Briscoe        Ganassi/Chevy    219.745  40.9566s  +0.6081s  15
16.  Alex Tagliani       Fisher/Honda     219.557  40.9917s  +0.6432s  25
17.  Oriol Servia        Rahal/Honda      219.150  41.0678s  +0.7193s  5
18.  Marco Andretti      Andretti/Honda   218.447  41.2000s  +0.8515s  6
19.  Takuma Sato         Foyt/Honda       217.840  41.3147s  +0.9662s  13
20.  Graham Rahal        Rahal/Honda      217.454  41.3881s  +1.0396s  16
21.  Sage Karam          Ganassi/Chevy    217.310  41.4154s  +1.0669s  77
22.  Josef Newgarden     Fisher/Honda     216.257  41.6172s  +1.2687s  5
23.  Martin Plowman      Foyt/Honda       216.165  41.6348s  +1.2863s  30

All drivers use Dallara chassis