Dale Coyne Racing's joy at putting Justin Wilson through to the Firestone Fast Six in Saturday qualifying turned to dismay when the #18 car's times were deleted following technical inspection.
Wilson's car was found not to be fitted with either an on-board TV camera, or with the alternative 'dummy' equipment supplied by IndyCar to replace the camera with the same aerodynamic and weight characteristics and ensure no one gains unfair advantage. The failure was a breach of section 188.8.131.52 of the IZOD IndyCar Series rulebook.
As a consequence of the loss of his times, Wilson will lose his sixth place grid position and will have to start from the back for today's Sao Paulo Honda Indy 300 in Brazil. Takuma Sato also has a grid penalty for an unscheduled engine change, while Katherine Legge will have to serve a grid penalty held over from Long Beach where she was forced into changing two Lotus units in quick succession.
It looks like rain could be a major factor in the day's proceedings, with Sunday warm-up facing wet and windy conditions that are likely to persist into the afternoon.
Track workers had done their best to take care of large amounts of standing water that had collected overnight during torrential downpours, although there were still large puddles left on pit lane. While the rain had eased off to a relatively gentle but consistent rate by morning, the cars immediately started to throw up large rooster tails and struggled not to aquaplane off at the first opportunity.
Turn 11 proved to be an early problem, with Tony Kanaan, Sebastien Bourdais and Justin Wilson all having to take to the runoff in quick succession, although all three were able to get turned around and get back underway.
Even so, the conditions dictated that it was only a matter of time before the red flags started flying. The first was soon out for JR Hildebrand stalling in the turn 6 runoff area, and the track had barely gone green when Katherine Legge ended up stopping out on track down the back straight, requiring a lengthy recovery by the pick-up track to pit lane.
By this point, with only a little over ten minutes of the half-hour warm-up session remaining and no driver having had a chance to complete more than five laps, EJ Viso headed the timesheets with a lap of 1:39.1262s. That demonstrated just how poor conditions were, being almost 20s off the pole position lap set by Power during a dry Saturday.
Once things got back underway, Kanaan survived right-rear contact from Takuma Sato into turn 11 which wrecked Sato's front wing. Sato was handed a drive-thru penalty for having caused the contact. Fortunately Kanaan saved his car and kept going without bringing out out a caution, but another brief red followed just a few minutes later for Helio Castroneves stranding himself in the turn 3 run-off.
With the rain easing and a dryer line starting to emerge with each pass of the cars on the Firestone wets, the top time had dropped over a second and a half down to 1:37.5037s even in that brief four minutes of green flag track time, with Ryan Briscoe now boasting the fastest lap so far.
Once Castroneves' Penske car was re-fired, the track went green again with around four and a half minutes remaining and Ryan Hunter-Reay immediately slashed a second off Briscoe's previous benchmark. A run-off at turn 11 for Oriel Servia was dealt with by local track workers without the need for a caution, allowing the session to make it to the chequered flag.
By that time, Hunter-Reay had shaved off a few more tenths off his laptime to set a final best lap of 1:36.0166s, almost a second better than EJ Viso, with Will Power, Justin Wilson, Rubens Barrichello and Mike Conway also getting in some decent runs by the end.
Race officials also announced that the race start would be pulled forward by half an hour, to the earliest time allowed by the television coverage window (12 noon local time, 4pm BST) in response to the likelihood of further rain later in the day.
In the UK, television coverage is via Sky Sports. Their presenter Keith Huewen confirmed on Twitter that the network would accommodate the earlier start by switching the start of race coverage onto the Sky Sports F1 channel.
Full Sunday warm-up times and positions