Kimi Raikkonen will start the Brazilian Grand Prix with a different engine to that he used in qualifying.
Ferrari was forced to change it after discovering a potential problem with the power unit he used to qualify fourth on the grid.
Raikkonen will now race with an engine he used in practice at Mexico, which suffered a problem and caused him to pull off with a fire. That has since been repaired, so he will not take a grid penalty.
Also in pre-race trouble is Carlos Sainz Jr, whose Toro Rosso ground to a halt in the pitlane exit.
“Car turned off by itself,” said Sainz, who is likely to start from the pitlane if his gremlin can be fixed.