Let D be a loopless digon-free directed graph on n vertices. Based on row and/or column sums, what is the smallest N such that D can be imbedded in a regular tournament on N vertices? More particularly, what is the smallest order of a tournament with specified score sequence, which has the given digraph D as a subtournament? In this article, we give conditions for a specified tournament to be a subtournament of a regular tournament, originally determined by Moon.
Beasley, L. B., D. E. Brown, Embedding tournaments, Congressus Numerantium, 198 (2009) 207-210.