neck and neck

adjective

Nearly equivalent or even: close, nip and tuck, tight. See near/far/distance.

So close that the advantage or lead shifts from one to the other or is virtually indistinguishable, as in The two are neck and neck in developing a new operating system for the computer. The term comes from horse racing, where the necks of two horses in competition appear to be side by side. [Early 1800s] For a synonym, see nip and tuck.