The Team Penske driver narrowly missed out on pole position on Thursday, losing out to the Wayne Taylor Racing Cadillac of Renger van der Zande by just 0.007s.

Castroneves held the top spot for much of the session, but had already brought the #7 Acura ARX-05 into the pits when van der Zande was on his final flying lap.

He said he was already aware he had missed out on pole when the media assembled to take his photograph – only then to quickly move down the pitlane to greet van der Zande.

“I was telling them [the photographers] to get up, because they didn’t realize,” recalled Castroneves.

“They were like, ‘give me a pose’, but I was still connected to the pitbox and [Tim] Cindric was commentating the lap, [saying] that the guy [van der Zande] was on it.

“So I was like, ‘Guys, get out of here, I’m not on pole position!’ I already knew I got beat by 0.007s, which is incredible. It was awesome, qualifying like that was pretty cool.

“It shows, to be honest, that they [Cadillac] have much more than what we expected. It’s part of the game I guess, but you’ve got to still do it for 24 hours.”

He added: “I’m excited, the potential we have is great. However, I still think the Cadillacs are the favorites, because I do feel they are holding back.

“I’m not saying it’s impossible [to win], we’ve been in this situation before, we know we can be competitive for sure.”

Castroneves, who shares the #7 Acura with Ricky Taylor and Graham Rahal, made his first sportscar appearance since 2008 at Petit Le Mans last year in an Oreca 07 - the car on which the Acura ARX-05 is based.

The three-time Indianapolis 500 winner admitted he still has much to learn about endurance racing, especially as he didn’t race in the dark at Road Atlanta.

“At Petit Le Mans I didn’t drive [at night], because it was [Juan Pablo] Montoya’s turn; here there’s no choice,” he said. “I’ve got to learn to adapt quick.

“I feel we’re in a good place, but as a driver, there are so many details, I can still learn a lot. I don’t think I’m there yet, because of all these new elements.

“I’ll learn as it goes, but the good news is there’s a lot of room for improvement.”