Max Verstappen faced potentially seeing just the second pole position of his Formula One career taken away from him on Saturday as he was brought before the stewards in Mexico.
The Red Bull star, who has won the Mexican Grand Prix from further down the grid in each of the past two years, qualified fastest in a dramatic final session.
Verstappen already led the way heading into his final lap and then marginally bettered his time.
But that last flying effort came under yellow flags at the final corner, meaning the Dutchman should have slowed after Valtteri Bottas crashed into the wall ahead of him.
Bottas, who must finish within 14 points of teammate Lewis Hamilton to deny him a sixth drivers' title this weekend, was cleared of injury but Mercedes were still assessing damage to the car.
While Bottas, who qualified sixth, could be penalised for changes to his set-up required due to the damage, Verstappen had problems of his own.
Ferrari - who had Charles Leclerc in second and Sebastian Vettel third - were unhappy that Verstappen was able to improve his time despite the flags on his final run, even though he already held provisional pole. The Scuderia had been on pole in the previous five races.
The FIA laws state: "Drivers should reduce their speed and be prepared to change direction."
Verstappen himself suggested this was not the case and confirmation followed from F1 that the stewards had summoned the pole-sitter.
"I was aware that Valtteri crashed," he said. "It didn't really look like [I slowed], did it? No.
"I think we know what we are doing, otherwise we wouldn't be driving an F1 car. It's qualifying and you go for it. If they want to delete the lap, then delete the lap."
HAMILTON FIT AND FIGHTING
Verstappen's potential penalty and teammate Bottas' huge crash distracted somewhat from Hamilton's fortunes, as he qualified in fourth place.
He must finish on the podium to have any chance of wrapping up the championship in Mexico, yet the Briton was relatively pleased with the position he had left himself in.
Hamilton told Sky Sports: "I think third place was possible, but the last sector fell apart there. I'm generally happy. It's hard to keep up with the others, but we knew it would be difficult this weekend coming here. I gave it everything and it wasn't enough for pole but I think I got everything out of the car I could.
"It puts us in a fighting position for Sunday, so I hope we can get a good start."
Hamilton has won the title in Mexico during each of the last two years, but finished the races ninth and fourth respectively.
Verstappen has seven F1 wins in his career but none of those have come from pole.
Hamilton added: "The Red Bull, I think will be gone. They're always quickest here each year. I don’t know exactly why, but they’ve got a great chassis, and Max, it’s obviously one of his favorite tracks. So a podium is the goal, but obviously I'll try to win.
"I'm happy Valtteri’s okay, and now I've just got to see what we can do. I have no thoughts of the championship. I'm thinking, 'How can I win this race?'"
1. Max Verstappen (Red Bull)
2. Charles Leclerc (Ferrari)
3. Sebastian Vettel (Ferrari)
4. Lewis Hamilton (Mercedes)
5. Alex Albon (Red Bull)
6. Valtteri Bottas (Mercedes)
7. Carlos Sainz (McLaren)
8. Lando Norris (McLaren)
9. Daniil Kvyat (Toro Rosso)
10. Pierre Gasly (Toro Rosso)
2018: Max Verstappen
2017: Max Verstappen
2016: Lewis Hamilton
2015: Nico Rosberg
1. Lewis Hamilton (Mercedes) 338
2. Valtteri Bottas (Mercedes) 274 (-64)
3. Charles Leclerc (Ferrari) 221 (-117)
4. Max Verstappen (Red Bull) 212 (-126)
5. Sebastian Vettel (Ferrari) 212 (-126)
1. Mercedes 612
2. Ferrari 433 (-179)
3. Red Bull 323 (-289)
4. McLaren 111 (-501)
5. Renault 77 (-535)
As if qualifying was not chaotic enough, there is 59 per cent chance of rain on race day, with the potential for heavy showers midway through proceedings.