Palou had a healthy 5s lead over Team Penske’s Josef Newgarden going on to the final lap but came across Armstrong on the approach to The Kink – one of the fastest and most fearsome corners in American motorsports.
Armstrong – who previously tumbled down the order due to a strategy error – had gone off at the Carousel and rejoined directly in front of the race leader.
Fortunately, he was told over the radio that Palou was approaching, whereas the Spaniard had no radio communications at that part of the track, before sweeping around the outside of Armstrong.
“Honestly they couldn't tell me because from Turn 8 until Canada Corner, there's no radio,” revealed Palou.
“Well, it's very hard [to hear], so we decide not to talk on those corners to avoid misunderstandings. They couldn't really tell me.
“Suddenly I saw a car. I didn't know it was Marcus. I don't know what happened to him.
“Yeah, [it was] quite on the edge there. Honestly, having a good five-second gap allowed me to just take it easy and overtake him.”
Armstrong, on the other hand, had been warned of the potentially disastrous situation.
“It looked fairly sketchy there, but I knew he was coming,” said Armstrong, who finished 24th.
“Someone told me on the radio that Alex was obviously leading the race and to let him through, so that’s what I did.
“It wasn’t an ideal way to finish the race but it’s something I’ll look back on learn from for next time.”
The Kiwi rookie, who has a best finish of eighth from his six outings to date in the Ganassi car he shares with Takuma Sato, drove a storming first half of the race to run with the frontrunners. This included moving eighth on the grid to third on the opening lap.
“If my memory serves me right, I had a good launch and took my chances around the outside,” he said.
“Someone braked too late in front of me [at Turn 1] and I picked up the pieces, so I was actually trying to be conservative.
“I crossed over with Newgarden [who went on to finish runner-up] at the exit of Turn 5, I wasn’t trying to do anything special, but picked up five spots.”
But his race fell apart with a strategy blunder that left him out on track during a caution around half distance, during which the majority of cars pitted.
Although he led for five laps, he was forced to pit under green and tumbled to the rear of the field.
“It didn’t work out in our favour unfortunately,” he admitted.
“It’s one of those things, being a strategist in IndyCar might be one of the most difficult jobs in motorsport. We’re going to learn from this, move forward and get the result next time.”
UPDATE: Chip Ganassi Racing confirmed today that Takuma Sato will return for the remaining oval events on the IndyCar Series schedule in the #11 car. He will test on Wednesday at Iowa, ahead of July's double-header event.
