Hi papagar. You just need to concentrate in your play and enjoy. Why do you play chess in first place? To chase cheaters or to have a good time playing? It is not possible to control nor ask other people to take care of cheaters, and enough discussion exists about cheaters see for example; http://www.chess.com/forum/view/livechess/cheaters Play the game and enjoy. If you lose to a much higher rater player then so be it. Cheers.
Why Chess.com 22nd Tournament organizers allow dishonest players?

Hi LikeTheLake and thanks for your answer.
As you said, I must concentrate in my game and enjoy it. But the problem is that I can't enjoy a tournament nor have a good time if I know that someone is cheating me and is taking me the opportunity to classify to the next phase.
Anyway, I learnt that in this cases we must contact directly to the staff in http://support.chess.com/Knowledgebase/Article/View/124/0/cheaters--cheating-what-you-need-to-know . (The staff consider cheating "fixing game results by playing with multiple accounts or losing intentionally").
So, I think this cases must be denounced, don't you?
I signed eagerly in the 22nd Chess.com 22nd Tournament, but I found that a player in my group is a cheater and this has disapointed me a lot, and probably there are many others like him in the tournament.
This guy had and average of more that 1900 ELO point during last months and just one week before the tournament, he lost some games in just one move and his ELO dropped 400 points. Unfortunatly he's now in my group.
If this dishonestity is easily identifiable, I'd like to ask the organizers why this behaviour isn't punished (for example with disqualification).
I signed to the tournament to enjoy with other people this great game, but also to give my best to win (to win against my peers) and not to lose the opportunity to classify to the next phase due to a dishonest player 400 ELO points stronger than me.
I hope for future competitions can be implemented some measures to avoid these drawbacks.