Barber IndyCar: Helio Castroneves on top on Friday

On an afternoon where several drivers enjoyed a stint at the front as the track improved and teams tried different approaches with tyres, Castroneves finished up as the benchmark with a best time of 1m08.5540s.

He is one of three Penske drivers this weekend, as he and Will Power are joined by single-seater returnee AJ Allmendinger.

"Obviously with the stoppage in the end a lot of guys probably put on new tyres, but the car felt pretty good," he said. "With AJ and Will, we've been actually doing a lot of different stuff out there and it seems to be working."

Alex Tagliani was second fastest for Bryan Herta Autosport, just ahead of the morning session's pacesetter Tristan Vautier, the Frenchman's Schmidt team-mate Simon Pagenaud, and Power, who had earlier been the first driver of the weekend to drop into the 1m08s range.

Despite his strong start, Vautier was reluctant to read too much into his early pace.

"I think that I still have some room to keep improving, and we need to carry the momentum from today into tomorrow," he said.

"It's a lot of fun out here, there's a lot of grip and the track was very fast. You can really enjoy the grip that those tyres produce. Especially on fast corners; you can really feel what the cars are capable of."

EJ Viso managed to finish up just behind Scott Dixon with the seventh-best time despite causing a late red flag courtesy of a trip into the gravel at Turn 9, while the encouraging start to Allmendinger's single-seater comeback continued with the Penske racer going eighth fastest.

James Jakes and Takuma Sato completed the top 10.

Pos  Driver               Team/Car                   Time        Gap
 1.  Helio Castroneves    Penske Dallara-Chevy       1m08.5540s
 2.  Alex Tagliani        Herta Dallara-Honda        1m08.6288s  + 0.0748s
 3.  Tristan Vautier      Schmidt Dallara-Honda      1m08.6720s  + 0.1180s
 4.  Simon Pagenaud       Schmidt Dallara-Honda      1m08.7627s  + 0.2087s
 5.  Will Power           Penske Dallara-Chevy       1m08.8066s  + 0.2526s
 6.  Scott Dixon          Ganassi Dallara-Honda      1m08.8446s  + 0.2906s
 7.  EJ Viso              Andretti Dallara-Chevy     1m08.8556s  + 0.3016s
 8.  AJ Allmendinger      Penske Dallara-Chevy       1m08.9119s  + 0.3579s
 9.  James Jakes          Rahal Dallara-Honda        1m08.9479s  + 0.3939s
10.  Takuma Sato          Foyt Dallara-Honda         1m08.9817s  + 0.4277s
11.  Justin Wilson        Coyne Dallara-Honda        1m08.9917s  + 0.4377s
12.  Ryan Hunter-Reay     Andretti Dallara-Chevy     1m09.0524s  + 0.4984s
13.  Oriol Servia         Panther/DRR Dallara-Chevy  1m09.1384s  + 0.5844s
14.  Dario Franchitti     Ganassi Dallara-Honda      1m09.1942s  + 0.6402s
15.  James Hinchcliffe    Andretti Dallara-Chevy     1m09.2602s  + 0.7062s
16.  Tony Kanaan          KV Dallara-Chevy           1m09.2755s  + 0.7215s
17.  Simona de Silvestro  KV Dallara-Chevy           1m09.2779s  + 0.7239s
18.  Charlie Kimball      Ganassi Dallara-Honda      1m09.3234s  + 0.7694s
19.  Marco Andretti       Andretti Dallara-Chevy     1m09.3452s  + 0.7912s
20.  Sebastien Bourdais   Dragon Dallara-Chevy       1m09.3480s  + 0.7940s
21.  Josef Newgarden      Fisher Dallara-Honda       1m09.5084s  + 0.9544s
22.  Graham Rahal         Ganassi Dallara-Honda      1m09.6315s  + 1.0775s
23.  JR Hildebrand        Panther Dallara-Chevy      1m09.7176s  + 1.1636s
24.  Ed Carpenter         Carpenter Dallara-Chevy    1m10.2947s  + 1.7407s
25.  Sebastian Saavedra   Dragon Dallara-Chevy       1m10.4443s  + 1.8903s
26.  Ana Beatriz          Coyne Dallara-Honda        1m11.2361s  + 2.6821s