I had exactly the same experience. And absolutely nothing was done about it.
How to report a cheater?
You can report a suspected cheater on this page: http://support.chess.com/index.php?_m=tickets&_a=submit .
Please note, discussion of cheating is not allowed in these forums, and this thread is likely to get locked soon due to this rule.

He didn't play that good in the game against you. When people cheat using a chess engine the moves are much better.
I believe he is a player who's rating should be arround yours, but he loses games against low rated players to be low rated himself.
This is would be a way of cheating, anyway. With low rating he can play in some Championships with rating limit and win easily.

Report your suspicions of cheating DIRECTLY to chess.com - via the Help & Support link at the bottom of every page - then Contact Us.
It's against site policy to accuse another member publicly.

I too have had the same situation. A player doing badly, goes off-line, and comes back making a GM move. Unforunately, it is hard to prove. You just have to choose not to play them and block the user in your account settings.

Report your suspicions of cheating DIRECTLY to chess.com - via the Help & Support link at the bottom of every page - then Contact Us.
It's against site policy to accuse another member publicly.
I accuse artfizz of being correct.

I too have had the same situation. A player doing badly, goes off-line, and comes back making a GM move. Unforunately, it is hard to prove. You just have to choose not to play them and block the user in your account settings.
I wouldn't recognise a GM move if it danced in front of me naked.

I wouldn't recognise a GM move if it danced in front of me naked.
That would certainly make for a more interesting game.

You're still playing that game, and you made some obvious errors...looks like sour grapes to me...
Maybe you are right about sour grapes, but you can't contradict the obvious difference between the games. I absolutely agree with Oliveira (keeping your rating down on purpose and so ruin others' ratings counts for cheating), and just note that I didn't accuse of using analyse programs. Finally sorry for opening the topic concerning the site's policy, I will delete it.

Check his other games.
Quick! Windows can show you every shortcut you need to block them!

I think you gave him too many chances....though I will admit his endgame skills are quite superior to his earlier playing efforts, and that is the area where expertise usually kicks in.

He didn't play that good in the game against you. When people cheat using a chess engine the moves are much better.
Using an engine, or playing a perfect game, is not the only way to cheat. I am not a great player, but I have some friends who are. So suppose that I play a player better than I am, and get help in the game from one of my friends. Suppose that this friend is a very good player, but still far from perfect. Then the narrow definition of cheating would say that this is OK?
Ha ha, I think the only thing lamer than cheating in online chess is acting like the chess police trying to sniff out cheaters. Relax, it's just one game. If a person really is cheating they'll be found out eventually.

Your logic baffles me. They will be caught eventually if we as a group try to shut them down. If, on the other hand, we go your way and stand down, then of course they will not be caught.
Your logic baffles me. They will be caught eventually if we as a group try to shut them down. If, on the other hand, we go your way and stand down, then of course they will not be caught.
If you think someone is cheating, why not block them so they don't bother you anymore. If you're really upset report them to the moderators. But there's no need for "us" to band together in a giant witch hunt on the forums every time someone plays a game "too well". Read the FAQ: http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=711
Hi all,
I opened this topic, because I have run into a rather odd case with a 1200- chess player, who is playing several spectacularly poor games (losing in 6-10 moves; some examples: [deleted by moderator] against players around 1300 and simultanously he's on the way to beat me (1640) in a fierce match of 50+ moves [deleted by moderator] This is more than suspicious for me, and that is why I am wondering is there an option to report some players of whom we are quite sure they are cheating? Any kind of posts concerning this topic is appreciated.
[Note from moderator:
Accusing players for cheating publicly in the forums is not allowed. If you want to report someone for suspected cheating, you can send tickets to the staff here:
http://support.chess.com/index.php?_m=tickets&_a=submit ]