Red Bull and Alfa Romeo have opted to introduce fresh engines in Austin for Sergio Perez and Zhou Guanyu that will set both drivers back by five spots on Sunday's US Grand Prix grid.
Both drivers were the recipient of a fifth internal combustion engine (ICE) this season.
The changes won't help Perez' chances of fending off Ferrari's Charles Leclerc in the Drivers' standings, with the pair battling for the runner-up spot behind freshly crowned F1 world champion Max Verstappen.
But it also won't strengthen Red Bull's chances of clinching the Constructors' title, although the Milton Keynes-based outfit still hold a nearly unbeatable lead of 165 points over Ferrari.
The Mexican is current one point ahead of his Ferrari rival with four races to go this season.
Zhou's allocation of fresh power will hopefully boost Alfa Romeo's chances of returning among the top-ten, a position the Swiss outfit has enjoyed only once in the last nine races.
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