Kasparaov's most important contribution to chess is the door-slam attack, where he showed how you can intimidate a much younger opponent by sheer display of pique. In the 1995 World Championship, Anand defeated Kasparov in game 9 to take the lead. In game 10, an enraged Kasparov employed a new technique. Every time he made a move, he would get up to go to the bathroom and slam the door behind him so hard the room shook. The young and mild mannered Anand was too rattled to complain to the arbiter. And the arbiter did nothing on his own.