Fianchetto Defense

The Fianchetto Defense, also known as the Smyslov Defense, the Barnes Defense or the Pillsbury Defense, meets the Spanish bishop with 3...g6. Black intends ...Bg7, placing the bishop on the long diagonal where it supports e5 and eyes the center. The move does nothing to challenge the bishop on b5 or to slow White's development, so natural replies such as 4. O-O, 4. Nc3 and 4. c3 are all playable. Castling is the most common choice, with 4. Bxc6 next. Vasily Smyslov and Boris Spassky turned to the line on occasion, and it gained a following in the 1980s once 4. c3 a6 was shown to give Black a good game. After 5. Ba4 that line transposes to the Fianchetto Defense Deferred. Against 4. c3 Black may instead try 4...f5, the Kevitz Gambit.

The critical test is the immediate central break 4. d4 exd4 5. Bg5, which is regarded as favoring White. This finding made the defense a rarity at master level. Alexander Khalifman has also recommended the gambit 4. d4 exd4 5. c3, whose positions remain lightly explored. Engines give White a slight edge, while online results are close to even.