Plaintiff sues to recover the contract price of his professional services. In order to succeed he must show at least substantial performance of his contract. It is certain that there has been none here. He contracted to box ten rounds under certain rules. At the outset of the contest, in the middle of the second round, he violated one of *427the rules and as a result thereof disabled his opponent and thus by his own act made substantial performance impossible. Whether this act was deliberate or not cuts no figure. It was an act which he had contracted not to do, and it prevented performance. Jennings v. Lyons, 39 Wis. 553. It does not seem necessary to consider other questions; the considerations suggested are decisive.

By the Gourt. — Judgment affirmed.