After heavy rain in the morning left the first practice session of the day in Detroit blighted by standing water, it was a much drier picture for the later afternoon second practice on the streets of Belle Isle.
Following disappointment at Indianapolis last weekend, Will Power resumed normal service by putting Penske top of the timesheets with a lap of 1:12.8355s (102.313mph), less then a tenth of a second ahead of Justin Wilson who had clearly rebounded from his minor mishap in the earlier session.
Power was clearly enjoying himself: "It's insane how hard you've got to push to be quick. It's great. There's no straights, there's no corners, and I had a lot of fun actually," he said.
For Wilson, it was good to be back at a circuit where he won the last time there was an IndyCar race here. "It seems like 2008 was a long time ago. We're back with new cars, new teams and new set-ups but the same track - I think we know what it takes to get around this place," he said. "It's always good to be back at Detroit. We've had a good day."
The one hour session saw two red flags, one early for Scott Dixon spinning through turn 13 and stopping in the middle of the track in the opening minutes, and the second just before the end for a sin and stoppage by Simona de Silvestro in the same sector.
"I spun in the first part of the second session. The car just felt really light on grip, and we struggled that session," explained Dixon. "I think we were decent enough to stay in the top five or six but we had a time in the car to be about third. Overall we're struggling with grip and balance."
One feature of the session was some close encounters with the local wildlife, with Rubens Barrichello being forced to swerve at speed to avoid a squirrel that encroached onto the track. Another squirrel leapt out in front of Sebastien Bourdais and wasn't so lucky.
Saturday sees another one hour practice session at 9am ET (2pm BST) ahead of qualifying at 11.45am (4.45pm BST). The Chevrolet Detroit Belle Isle Grand Prix takes place on Sunday afternoon at 3.45pm (8.45pm BST) after a final early morning half-hour warm-up opportunity.
Full practice 2 times