Chess opening are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense (see diagram) which yields an immensely complicated and tactical position that even strong players have difficulty handling, and that is beyond the comprehension of most amateurs. Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as does Pedro Damiano (1512), and Ruy López de
Ruy Lopez Leko used the Marshall to win an important game against World Champion Vladimir Kramnik. Currently, Armenian Grandmaster Levon Aronian is one of the main advocates for the Marshall Attack. The main lines of the Closed Ruy Lopez continue 6.Re1 b5 7.Bb3 d6 8.c3 0-0. White can now play 9.d3 or 9.d4, but by far the most common move is 9.h3 which prepares d4 while preventing the awkward pin ...Bg4. This can be considered the main line of the opening as a whole and thousands of top-level games have reached this position. White aims to play d4 followed by Nbd2–f1–g3, which