Trees with three leaves are (n + l)-unavoidable

We prove that every oriented tree of order n ≥ 5 with three leaves is (n + 1)-unavoidable. More precisely, we prove that every tree A of order n with three leaves is contained in every tournament T of order n + 1 except if T is the regular tournament on five vertices and A the outstar (instar) of degree three, that is, the tree consisting of a root dominating (dominated by) three leaves.