Liam Lawson will start Sunday's Mexico City Grand Prix from the back of the grid after his strong performance in Saturday's qualifying was erased for technical reasons.
The Racing Bulls driver had qualified a promising ninth ahead of teammate Arvid Lindblad in a thrilling session topped by seven-time world champion Lewis Hamilton in a Ferrari.
It was a record-extending 105th pole position for the Briton and his first for the Italian team.
The luckless Lawson, who is fighting to keep his seat for 2027, had his laps deleted after an inspection revealed his power unit's output fell outside the regulations.
The infringement was noted as the 24-year-old crossed the line at the end of his fastest lap in Q2 when he had exhausted his battery energy.
The regulations require electrical power to decline at a controlled and progressive rate, not abruptly.
In a statement, the race stewards said Lawson "did not lift off the power immediately" as expected.
His demotion on the grid comes on the back of a tangle with four-time world champion Max Verstappen of Red Bull during Friday's practice, resulting in both drivers receiving a one-place grid penalty.
Lawson apologised to Verstappen, who will start from fifth, on Saturday morning after another incident-filled session in which he claimed his bid for pole was thwarted by outgoing world champion Lando Norris's McLaren.
He said Norris was running slowly on the racing line and ruined his lap as he locked up and lost time.
"When I saw his car on the right, I couldn't believe my eyes," said Verstappen.
"I was fighting for pole."
Verstappen also spoke out to support his teammate Isack Hadjar after the Frenchman had been officially reprimanded for pushing aside an aggressive fan demanding a selfie with him in the chaotic paddock on Friday.
"I understand his reaction," said the Dutchman.
"It's incredibly irritating when people just touch you without asking… I've never pushed anyone away, but there have been times when I came close.
"I've compared the paddock to a zoo before -– and this is the situation you get when you let so many people in."
Hadjar was relieved to receive a warning and not a more severe punishment.
"It makes sense and I'm glad they made the right decision," he said.
"Fair play. I'm going to work. It's not a reality show and I am going into the garage."