If you are new to watching NASCAR and the cars are doing pace laps before the green flag flies, starting or restarting the race, sometimes it can be a dramatic experience, waiting to see that green flag fly!
But seasoned fans know if the pace lap they are watching will be leading to the green flag or another pace lap.
It is pretty easy actually.
Just look at the light bar on the pace car leading the pack around the track.
On oval tracks the light bar is always flashing. But with one lap to go before the green flag, the lights go out on the pace car.
On road courses, the lights go out with less than half a lap to go. That is because road courses are different beasts, with much longer and slower pace laps.
Now you know. Go watch the race and have fun.