Wis. Stat. § 945.07: Gambling by participants in contest.

(1) Any participant in, or any owner, employer, coach or trainer of a participant in, any contest of skill, speed, strength or endurance of persons, machines or animals at which admission is charged, who makes a bet upon any opponent in such contest is guilty of a Class A misdemeanor.

(2) In this section, “participant” includes any person who is selected or who expects to take part in any such contest.