I have a friend who is an improving chess player. He wants to progress in his game. The problem with him is that he plays really good with much stronger opponents but, often lose many games surprisingly with even much weaker opponent which makes him less-confident. I really want to solve his problem by understanding his psychology but i can't. Would anyone like to help me to solve his problem? Is there any chess course to help him out... ?
I think it's really a common problem. Many people facing stronger opponents are playing for a draw, even as white. I think that the key is to wait and let them commit mistakes instead of going Rambo-mode. I did it myself on Sunday. I lost a game to a much weaker opponent just because I went kamikaze instead of pushing the wood slowly. He should try to stay cool. A draw is not a bad result at all.
I think it's absolutely natural:
Playing against strong players is often much easier. You can’t lose anything, you can only win. I personally have often the problem playing against strong players that I think I probably will lose and am too much passive, that my opponent often has too much time to rise his power against my vulnerable kingside.
Playing against weak players can rise pain of losing. Each player has to be aware, that losing against a weaker player is not a shame, it often depends that the outcome of an unusual opening will be unclear.
I would give him following advice to improve his chess skills playing against weaker player:
If he plays against weak player he should play continuous and not try to create complicate mating nets which are often unclear.
May be he should play many times in succession against weak player in order to reduce his worry of losing.
He should read good books about chess psychology. I personally have profited much studying the book "Devious Chess - How to bend the rules and win", a book from Amatzia Avni, a master chess psychologist who has studied psychology in Israel and has written a number of books on chess psychology, published by Batsford.
You could post an example of a game where he lost against a weaker opponent and we could try to pinpoint the mistakes he makes, in a more abstract way. Generally speaking, as pointed out by others, this is not an uncommon problem. People get overambitious when pressing for a win against a weaker player, but play very safely when playing against a stronger player, since a draw would be sufficient. Another reason could be, I suppose, that he is very good at opening theory but lacks skills in other areas. When playing against weaker players, this illusion of the guy who can withstand the strong opponents collapses, because he doesn't know how to punish non-standard, suboptimal moves.
To avoid getting frustrated, I suggest that your friend trains more (if he is looking for the most efficient method: 30 mins to 1h tactics a day + playing lots of tournaments). This enables him to maybe get rid of his issue through accumulation of knowledge, or, if this doesn't happen, compensate for his frustration over the losses against weaker players through a general improvement.
With ascending skill and experience, you can learn which positions to avoid and which to seek against weaker players. For example, if you are playing the Semi-Slav, start with e6 instead of c6 against a weaker player, because he might enter the Exchange Slav, which is known to be very drawish. Hope I could help you a bit with those thoughts.