Dale Coyne Racing's Pippa Mann and AJ Foyt's rookie Conor Daly were among those still on pit lane in their firesuits in case they had to jump into action. They couldn't take pre-emptive action without officially withdrawing their existing times, which they weren't about to risk until Jourdain looked like he might have something to offer.
The driver most at risk was Katherine Legge, who only arrived at IMS on Saturday for her seat fitting with Schmidt-Peterson Motorsport but who managed to just make the grid with a four-lap average time of 223.176mph. That put her in 33rd position on the grid and officially 'on the bubble' in Indy qualifying parlance, and on tenterhooks all afternoon waiting for Jourdain to set a flying lap time which might drop her out of the race just 24 hours after her surprise call-up at in the third Schmidt-Peterson car alongside regular drivers Simon Pagenaud and Tristan Vautier.
"Relief!" said Legge as she saw Jourdain's crew finally packing up. "Obviously, it's not nice to do it in that manner; I feel bad for Michel. It's not nice for him to not have the opportunity.
"However, I am happy I am in the field, I'm not going to lie about that!" she added. "I'm going to sleep tonight for the first time in a few days. I feel really bad for Michel. I can't even think what's going through his head. I'm gutted for him."
Legge's time might have been the slowest of anyone on Bump Day, but considering how little time she'd had in the cockpit it was something of a minor miracle that she was able to set anything like a flying lap so soon in unfamiliar equipment.
"I had less than 20 when I went out to qualify, but apparently so the team tell me I was flat on Lap 4 of being in after not being in one of these cars for several months," she said. "I was aware there was a condensed schedule, so I had to get after it, and we have done a bit today.
"Our race car is really nice," she continued. "I feel really comfortable, ran in traffic a bit. We didn't have to trim out, so I have no idea what the car is like trimmed out. We'll have to go and do that, and there would have been another couple of miles an hour in it, so I think we were confident we were in the field."
Legge also spoke of how the last-minute Indy deal with Sam Schmidt had come about in the first place following her acrimonious and still-disputed split with Dragon Racing at the end of 2012.
"I was talking to him since 2011," she explained. "I put my name on his radar and bugged him for a while, and I think for this particular race I was working really hard since things blew up at the beginning of the year for me. I was working really hard to find a ride for the 500 at the very least, and possibly with other races."
In her time away from IndyCar Legge got to race the DeltaWing in last month's American Le Mans Series race at Laguna Seca in Montery, California, and the English driver said she hoped that she'd get more runs in the innovative prototype regardless of what may or may not happen for her in open wheel racing this season.