Team Penske driver McLaughlin and Andretti Autosport’s Grosjean were battling over the lead after the final round of pitstops, having earlier almost come together at Turn 4 after the first pitstop sequence.

With 28 laps to go, leader McLaughlin emerged from the pits on cold tyres, with Grosjean – on recently changed and fresh hot rubber – right behind him. As they charged towards Turn 4, Grosjean attempted to outbrake him around the outside but McLaughlin also went deep under braking, locked his rears and took them both out into the tyre barrier.

Grosjean was out on the spot, while McLaughlin was bumpstarted and rejoined. He was given a drive-through penalty for unnecessary contact and went on to finish the race in 13th, while Grosjean was classified 18th.

“First and foremost, I’m very sorry to Romain, he’s a friend of mine, and I know we were both going for the win there,” McLaughlin told NBC. “I just made a big mistake.

“I tried to push on cold tyres, I just didn’t have the grip there like I did on the greens [Firestone's alternate tyre] and locked the rears, and unfortunately we made wheel contact this time that took us both out.

“Look, I don’t race like that. I apologise, I feel that I’ve had many good battles with many good drivers, just gutted for my crew. The fuel mileage was great and I just made a stuff-up, man.

“You have those: you have your good days and bad days, and I really do have to apologise to Romain. I’ll go and see him soon.”

When informed that his 13th-placed  finish meant it wasn’t such a bad day for him in the championship race, as many expected frontrunners struggled, McLaughlin elaborated: “I concentrate on my own mistakes, I need to be better than that and make better decisions.

“Ultimately, I think I was just racing for the win, I knew we could have had a chance if we’d got out in front of him at Turn 4.

“Big apologies. I was just racing hard, man, I promise I don’t race like that, so I’m very gutted. We finished the race, but I’ll go man-up and see Romain now.”

Grosjean, who thumped the tyre wall in anger after his removal from the race, believes that IndyCar should review its racing rules.

“What happened was what you can see on TV, so I don't want to elaborate too much on that,” said the former F1 ace. “I'm very disappointed and I hope there's going to be rules put in place.

“We had a really fast car, the team did an amazing job, but I'm really annoyed to be talking while the race is still going on.”

When asked if he still had respect for McLaughlin, Grosjean added: “I still admire what he's done, coming from V8 Supercars and he has done a really good job, but what we saw today on track is not racing.”

Speaking after the race, Grosjean later confirmed that McLaughlin offered an apology for the error that ended his victory hopes. 

“We all race, we all make mistakes,” said Grosjean. “Scott came over and apologised, which means everything to me. He did get a penalty. Unfortunately, that doesn’t really change anything for my race, but the fact that he comes here and says he’s sorry is a big deal.

“I know that we were the fastest car on track by a long way and that’s all that matters. We were competitive, we were up there and we have 16 races left. We showed today with Andretti that we can be up there."