Three-time Indianapolis 500 winner Helio Castroneves set the fastest speed at the Indianapolis Motor Speedway in an afternoon practice session disrupted by the threat of lightning.
The Penske driver made his racing return to IndyCar at last weekend's Indianapolis road course event, where he finished sixth, ahead of his attempt to win a fourth Indy 500.
Castroneves was able to set the fastest time with and without a tow on track, as IndyCar teams began drafting at Indy for the first time as the field learns how the new 2018 aerodynamic package behaves on the superspeedway in race-like conditions.
The Brazilian set his best lap speed of 224.665mph inside the final hour after running was delayed for half an hour due to lightning in the vicinity of the track, adding to earlier brief delays for spots of rain.
Despite fears that the conditions would lead to team's ending their running early, the majority of the day's fastest lap speeds were set in the final hour.
Ed Carpenter was second quickest for his namesake team, trailing Castroneves' benchmark by 0.124mph.
Schmidt Peterson Motorsports' one-off entrant Jay Howard was third, narrowly holding off a late improvement from Scott Dixon in the final minutes.
Marco Andretti had been second on the timesheets ahead of the frantic final hour but he slipped to fifth late on.
Dreyer & Reinbold Racing's Sage Karam was sixth ahead of Carlin man Charlie Kimball.
Gabby Chaves made it five Chevrolet-powered cars in the top 10 with eighth for Harding Racing, ahead of Andretti duo Zach Veach and Ryan Hunter-Reay.
Simon Pagenaud had topped the morning's earlier practice session in a Penske 1-2-3 ahead of Castroneves and Newgarden, aided by a tow from Will Power.
But Pagenaud was just 14th in the afternoon, ahead of Robert Wickens (SPM) and Dale Coyne Racing driver Sebastien Bourdais.
Rahal Letterman Lanigan Racing had impressed in the first practice session with Takuma Sato and Graham Rahal, who were the quickest drivers without a tow in the early running, but it ended the afternoon with Sato pulling off track with a problem in the final minutes.
Danica Patrick ended the day in 18th place, with Penske's Power, Newgarden and 2016 Indy 500 winner Rossi down in 22nd, 23rd and 26th respectively.
Zachary Claman de Melo completed his rookie orientation programme just hours after the Indy Lights graduate was confirmed as the replacement for the injured Pietro Fittipaldi for the Indy 500.
Andretti's Stefan Wilson, who stepped out of a drive for last year's race so the team could run Fernando Alonso, passed his veteran refresher test.
Oriol Servia, in the RLLR-prepared Scuderia Corsa-affiliated car, also passed the refresher test, as did AJ Foyt Racing's James Davison - a late stand-in for the injured Sebastien Bourdais last year.
Conor Daly was able to make the track in the final minutes after DCR had been preparing his car through the day, meaning Foyt's Matheus Leist was the only driver not to lap the Indy 500 venue.
Tuesday practice times
|1||Helio Castroneves||Team Penske||Dallara/Chevrolet||224.665||40.0597s||38|
|2||Ed Carpenter||Ed Carpenter Racing||Dallara/Chevrolet||224.523||40.0850s||39|
|3||Jay Howard||Schmidt Peterson Motorsports||Dallara/Honda||224.518||40.0858s||69|
|4||Scott Dixon||Chip Ganassi Racing||Dallara/Honda||224.353||40.1153s||33|
|5||Marco Andretti||Andretti Herta||Dallara/Honda||224.217||40.1397s||36|
|6||Sage Karam||Dreyer & Reinbold Racing||Dallara/Chevrolet||223.998||40.1790s||60|
|8||Gabby Chaves||Harding Racing||Dallara/Chevrolet||223.640||40.2433s||29|
|9||Zach Veach||Andretti Autosport||Dallara/Honda||223.551||40.2592s||45|
|10||Ryan Hunter-Reay||Andretti Autosport||Dallara/Honda||223.488||40.2707s||66|
|11||Spencer Pigot||Ed Carpenter Racing||Dallara/Chevrolet||223.398||40.2868s||38|
|12||James Davison||AJ Foyt Enterprises||Dallara/Chevrolet||223.346||40.2963s||21|
|13||Takuma Sato||Rahal Letterman Lanigan||Dallara/Honda||223.305||40.3037s||49|
|14||Simon Pagenaud||Team Penske||Dallara/Chevrolet||223.284||40.3074s||57|
|15||Robert Wickens||Schmidt Peterson Motorsports||Dallara/Honda||223.133||40.3347s||52|
|16||Sebastien Bourdais||Dale Coyne Racing||Dallara/Honda||222.960||40.3659s||46|
|17||Ed Jones||Chip Ganassi Racing||Dallara/Honda||222.848||40.3863s||39|
|18||Danica Patrick||Ed Carpenter Racing||Dallara/Chevrolet||222.728||40.4080s||39|
|19||Carlos Munoz||Andretti Autosport||Dallara/Honda||222.701||40.4130s||50|
|20||Oriol Servia||Scuderia Corsa||Dallara/Honda||222.697||40.4137s||17|
|21||Stefan Wilson||Andretti Autosport||Dallara/Honda||222.524||40.4451s||36|
|22||Will Power||Team Penske||Dallara/Chevrolet||222.495||40.4504s||48|
|23||Alexander Rossi||Andretti Autosport||Dallara/Honda||222.471||40.4548s||68|
|24||J.R. Hildebrand||Dreyer & Reinbold Racing||Dallara/Chevrolet||222.256||40.4938s||38|
|25||James Hinchcliffe||Schmidt Peterson Motorsports||Dallara/Honda||221.900||40.5589s||31|
|26||Josef Newgarden||Team Penske||Dallara/Chevrolet||221.852||40.5675s||35|
|27||Graham Rahal||Rahal Letterman Lanigan||Dallara/Honda||221.671||40.6007s||64|
|28||Jack Harvey||Michael Shank Racing||Dallara/Honda||221.500||40.6321s||67|
|29||Tony Kanaan||AJ Foyt Enterprises||Dallara/Chevrolet||221.412||40.6482s||12|
|31||Zachary Claman||Dale Coyne Racing||Dallara/Honda||221.089||40.7076s||16|
|32||Kyle Kaiser||Juncos Racing||Dallara/Chevrolet||220.707||40.7781s||45|
|33||Conor Daly||Dale Coyne Racing||Dallara/Honda||215.926||41.6809s||9|
|34||Pippa Mann||Dale Coyne Racing||Dallara/Honda||214.731||41.9130s||19|