Lewis Hamilton, Andrea Kimi Antonelli and Fernando Alonso have all installed new power unit components on their Formula 1 cars, while Carlos Sainz has made car set-up changes, forcing them all into pitlane starts at the Belgian Grand Prix.
The first three mentioned suffered an early qualifying exit in Q1 on Saturday, relegating them to a back-of-the-grid start.
A marginal track-limits offence on the run through Raidillon meant Ferrari driver Hamilton's best time was deleted, demoting him to 16th.
Antonelli was 18th after another disappointing weekend as he struggles for confidence in the Mercedes, while Alonso only qualified ahead of Aston Martin team-mate Lance Stroll in 19th.
With all three drivers already on the edge of an engine-related grid penalty and still half of the 2025 season left to run, they have now used the opportunity to add fresh power unit components to their pool with minimal sporting consequences.
Hamilton, Antonelli and Alonso will all get a fifth new internal combustion engine, turbocharger and electric MGU-H and MGU-K units for Sunday's race, with only four allowed for the season. Hamilton has also refreshed the remaining power unit components on his Ferrari - the battery and control electronics - as well as taking a new exhaust.
Later on, the FIA confirmed Williams driver Sainz will also take a pitlane start after making set-up changes to his car under parc ferme conditions. The Spaniard had qualified 15th.
It means only 16 drivers will line up on the starting grid of the race, which is set to be held in mixed weather conditions after heavy showers hit the track on Sunday morning.
Hamilton didn't necessarily agree with the stewards' decision on his track-limits offence, but still took responsibility for his second consecutive Q1 exit this weekend after spinning out of sprint qualifying at the chicane.
"I don't agree, no. But I'm out," he said. "That's my mistake, so I'm just really sorry to the team for all the hard work, all the testing, the filming day that we did, and all the preparation. And then you come here and you don't even make it through Q1, which is unacceptable. I'm really sorry.
"There's always opportunities in the race, so we'll see what I can do from there."
Photos from Belgian GP - Race
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