Perhaps mindful of the rain radar showing worsening conditions rapidly approaching the 2.3-mile Barber Motorsports Park road course, Penske's Will Power was quick on his marks to get out and set what proved to be the fastest lap of the day early in first practice on Friday.
Power set his lap of 1:11.2886s (116.148mph) just his fast lap just after the 1pm, the halfway point of the hour-long practice 1 session that was divided into two half-hour groups with the earlier session reserved for rookies and drivers lower down the championship points.
"We have tested here a lot and know the track very well and the set-up very well," said Power. "We just made minor adjustments to the car because we basically know what we want.
Power's time was 0.2124s ahead of his team mate Helio Castroneves, and the Chevrolet 1-2 was mirrored by a Honda 3-4 which comprised Rahal Letterman Lanigan's Takuma Sato and Sarah Fisher Hartman Racing's impressive rookie Josef Newgarden.
"I think we had a good first session," said Newgarden. "We're certainly in the ballpark. We're not quite there, I think we need to make some adjustments and dial it in a bit more."
Rubens Barrichello looked comfortable to be on the sort of course that is much more familiar to him, and duly set the fifth fastest time of the session two hundredths ahead of Marco Andretti.
"What a difference it makes when you know the place," he agreed. "I have only done one test here, but it makes a huge difference compared to last weekend at St. Petersburg.
"Today was a day where I don't think anybody really had the chance to push the car to its limit," he continued. "It brings a new challenge to the weekend because we only have 20 minutes tomorrow before qualifying so we have a lot of work to do with the engineers tonight to make sure the car is good enough for qualifying."
The rain started to fall ten minutes from the end of the first session, but there were no significant incidents out on track despite the worsening conditions. However, back in pit lane the Dale Coyne Racing car of Justin Wilson suffered a fuel line fire in the engine compartment after just three laps of running. Wilson had to sit out the rest of the day while the team and Honda assessed the damage, to see if the fire was going to force them to change engines before Sunday's race.