The opposite of the front would be the back. That is because the front is the forward part or location, as of a building, and the back is the posterior part farthest from the front.
The opposite location of "in front" would be "out back" (behind). The opposite of being "in front" (in the lead) would be "in the rear" (trailing).
Commit
....behind/back and antonym would be anterior - in front/front
If the lead in the question is to be in front, then the opposite is to follow.
Front
A Cold front
a front-up
Behind
It is the Outback. (see related link)
the opposite of anterior is Posterior.
opposite front side
front