Sergio Perez believes running an extra set of Softs in the early stages of Mexico City Grand Prix qualifying cost him an improved grid position for his home race.
The crowd favourite put on an improved display to finish within two-tenths of teammate Max Verstappen at the Autodromo Hermanos Rodriguez.
Perez reached Q3 having completed an extra run in the opening two segments compared to his rivals, leaving him on the back foot for the final 12-minute shootout.
It proved to be costly, despite the marginalised gap to Verstappen, as the Mexican finished slower than both Ferraris - which locked out the front row - and AlphaTauri's Daniel Ricciardo.
Put to him that he would not have expected the Australian in front of him on the grid, Perez told media including RacingNews365.com: "Not a Ferrari either.
"But it is what it is. Our progression to Q3 wasn't great, we ended up losing a set [of Softs] that we potentially didn't need to, but you only know that after qualifying.
"That really hurt us and when you are talking about a tenth-and-a-half due to that, it would have changed our life completely."
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Ricciardo's return to F1 in place of Nyck de Vries at AlphaTauri ramped up the pressure on Perez, who has struggled to string together consistent patches of strong form across the season.
Whilst next year's seats are confirmed with contracts in place, Ricciardo is likely in line to take over from Perez if Red Bull's hierarchy deems a switch necessary.
On how he felt seeing his seat rival outqualify him in inferior machinery, Perez explained: "Daniel did a tremendous lap.
"I don't think it is just Daniel that wants my seat, let's say there are a lot of other drivers that want to be in my seat.
"It's great, if it's what they deserve, then happy for them."