A friendly between a Leeds United Under-23 team and Welsh side Rhyl FC was abandoned in the second half after a brawl between the two sets of players.
Leeds coach Carlos Corberan reportedly took his side off the field after punches were thrown.
Video footage shared on social media shows players from both clubs tangling before the Leeds players leave the pitch.
Rhyl FC say they will carry out an internal investigation.
Corberan defended his players and said on Twitter: "We will always represent Leeds United with the correct behaviours and values respecting the opponent and the football rules.
"(I'm) proud of the players in the way they conducted themselves."