Ruy Lopez Blue chess computer in Game 2 of their 1997 match. Svetozar Gligorić has been the most prolific C93 player. 9...Qd7 is another variation by Smyslov. Of the variations in this section, the Berlin and Schliemann Defences are the most popular today, followed by the Classical Defence. and other less-common third moves for Black. The Cozio Defence (part of "ECO" C60), 3...Nge7, is distinctly old-fashioned and the least popular of the defences at Black's third move. Although Bent Larsen used it occasionally with success, it remains one of the least explored variations of the Ruy Lopez. The Smyslov Defence, Fianchetto Defence,
Sicilian Defence most part, other moves are the Closed Sicilian. Possible moves are 3.g3 and 3.f4 in general, also 3.Nge2, and less commonly 3.d3 and 3.Bc4. Some lines may transpose to the Open Sicilian, but there are many that do not. Also of some interest is 3.Bb5 to ...Nc6. A typical line is 2...Nc6 3.g3 ("ECO" code B24). Also 2...Nc6 3.f4 is the Closed Sicilian, Grand Prix Attack (part of B23). White can also keep their options open with 3.Nge2. Andrew Soltis has dubbed that the "Chameleon System", since White maintains the option of playing a Closed Sicilian with 4.g3 or transposing