After finishing the Friday morning practice session in second place, Schmidt Peterson Hamilton Motorsport's Simon Pagenaud went one place better in the afternoon practice to set the fastest time of the day.
His lap of 1:00.1415s (97.809mph) on the the 1.634-mile, 10-turn temporary street circuit was half a second quicker than Ganassi Racing's Ryan Briscoe who was in second place in the timesheets, and was three-tenths faster than Will Power's pace-setting time from first practice.
"This car is a pleasure to drive," said Pagenaud afterwards. "It looks pretty strong right now. We just need to keep up with the track because the car was pretty much perfect today. If we're good tomorrow on the red Firestone tyres, we should be in good shape."
Luca Filippi continued to impress in his first single-seater outing of the year as he set the third fastest time of the session in the #16 Rahal Letterman Lanigan Racing entry.
"It would be good to have a car that is fast but, more than all, easy to drive so you can be consistent and drive around the bumps and in the heat; that's going to be tough," said Filippi, who drove here last year for Bryan Herta Autosport.
Pagenaud's impressive time meant that only 11 other drivers were within a second of his flying lap benchmark. However, disregarding Pagenaud's time reveals that 19 drivers are within a second of Briscoe's best.
The balance of power shifted slightly toward Honda in the afternoon, with six of their cars in the top ten compared with four Chevrolet entries - two Penskes and two Ganassi cars.
There were three red flags during the 45-minute session, the first coming just five minutes into the proceedings when Mikhail Aleshin spun in turn 4 and needed assistance to recover. The Russian was able to continue with practice and went on to set the fifth fastest time, despite a second spin later in the session.
The next red flag was sparked by Tony Kanaan spinning in turn 1 ten minutes into the session. He came to rest beached on the kerbing at turn 2 and needed the safety crew to help him get back underway.
The session ended under a final red flag when Jack Hawksworth managed to get launched skywards by the same raised kerbing exiting the turn 2 chicane that had caught out Will Power in the morning. Unfortunately in this case it ended up spitting the #98 Bryan Herta Autosport car into the wall where the it sustained some heavy front right damage.
After the debris from Hawksworth's wreck was cleared up, the drivers had an additional ten minutes of standing start practice on the main straightaway, to allow them to prepare themselves for the beginning of Saturday afternoon's race 1.
Qualifying for race 1 will take place at 10am (4pm BST) on Saturday morning with the race itself getting underway at 2.45pm (8.45pm BST). In the UK, the race will be shown live on ESPN.
Full practice 1 results
Full practice 2 results
Friday practice combined results