Engine component usage for the US Grand Prix

As the end of the season nears, engine component usage is logically reaching critical levels, with many drivers sitting right on the margin.

As a reminder, drivers are permitted to use only four of each of the six elements that make up the power unit under current regulations. Any more than that and they start getting some painful grid penalties.

• Specific parts still giving Renault reliability headaches

We've already learned that rookie Brendon Hartley will be dropped down the grid on Sunday, through no fault of his own as Toro Rosso changes an engine which has reached the end of its cycle.

But both Red Bull Racing drivers find themselves at risk of a demotion come race day. Last night the team was apparently debating with Renault whether to change Max Verstappen's unit or leave it installed for another week until Mexico.

Gallery: The beautiful wives and girlfriends of F1 drivers

Keep up to date with all the F1 news via Facebook and Twitter