Undercut

It works because a new tyre is at its fastest immediately, while the car still out is on rubber several laps older. One or two quick laps on the fresh set can be worth more than the position was — and because the rival only discovers it when they emerge behind, there is nothing they can do about it once it has worked.

The out-lap is where it is won or lost. A fresh tyre needs a lap to reach its working temperature, so the driver has to push hard on rubber that is not ready, without overdoing it and graining the surface. Get it right and the lap is worth a second or more. Get it wrong and the stop has cost track position for nothing.

It fails in predictable conditions: traffic on the out-lap, a circuit where the pit lane costs too much time, or a hot day where the tyre takes longer to switch on than the gap allows. It also fails when the car ahead simply responds — a team watching the timing screens can cover an undercut by pitting the very next lap, which is why teams try to disguise the call.

When the conditions are wrong for it, the mirror image is the move: stay out, use the clear air, and overcut instead.