Toro Rosso Formula 1 rookie Brendon Hartley is set to start his first grand prix from the back of the Austin grid due to engine penalties.
STR team principal Franz Tost confirmed to Autosport that Hartley will take a complete new power unit this weekend, and that the decision was made before it was confirmed that Hartley would be making his maiden F1 start in that car, which was driven by Pierre Gasly in the last two races.
Tost added that the sister entry will take new power unit elements in Mexico next weekend, with both cars simply running out of engine mileage with which to finish the season.
Although the exact size of the grid penalty has yet to be confirmed, a complete change for Hartley should be worth 30 places, as he will be on the car's sixth V6, turbo and MGU-H, and fifth energy store and control electronics. His use of a fourth MGU-K does not earn a penalty.
Sources have indicated that Red Bull's Max Verstappen is also set to take power unit penalties this weekend.
When asked about the prospect on Thursday, Verstappen would only say: "We'll find out tomorrow.
"I'm not sure whether it's going to happen here, or in the next races. You'll hear it tomorrow."