Tournaments with Cash Prize

I already wrote that our browser game has tournaments. On possible income source could be creating tournaments for money, just like chess or poker, where players would pay some money to enter and would receive a good cash prize. One special type of tournament of interest would be team tournaments, where players would team up and would have some objectives.

A problem  that we're facing on our turn based game, is how to prevent players from cheating the game. Imagine that I would contact another team, and we both would play for a defined victory. A team would sacrifice itself for the other. And on the end of the game, they'd just split the prize money. This isn't fair and we don't know how to prevent it. This may happen on battles that have more than 2 teams, and that was one of our options.

The other, probably more easy to implement is to have simple tournaments with 1on1 battles. Just like a chess tournament.