Owen Defense

The Owen Defense, also called the Queen's Fianchetto Defense and often reached by the order 1. d4 b6 2. e4, prepares ...Bb7 so the bishop can bear down on e4 and the long diagonal. The cost is that White can occupy the center at once, and 2. d4 is the most popular answer. Unlike 1...g6, the move does nothing toward kingside castling, and supporting the bishop with ...f5 loosens Black's king far more than the analogous ...c5 does in the Modern. The opening therefore has a dubious reputation, and engines give White a clear advantage, although results in online play are close.

After 2. d4 Bb7 the historical main line is 3. Bd3 e6 4. Nf3 c5 5. c3, which MCO-15 assesses as clearly better for White. The move 4. c4 instead transposes to the English Defense. IM Lawrence Trent regards 4...c5 as close to refuted and prefers 3. Bd3 e6 4. Nf3 d5. Then 5. e5 Ba6 gives an Advance French structure in which Black trades off the bad bishop, while 5. exd5 Qxd5 6. Nc3 Qd8 recalls a Scandinavian or an asymmetrical Exchange French. Specialist Pavel Blatny has favored 3. Bd3 Nf6, typically met by 4. Qe2 e6 5. Nf3 d5 6. e5 Nfd7 7. O-O c5, another French-style position. White can also protect e4 with 3. Nc3. Against it Black may continue with ...e6 and ...Bb4, or play 3...g6 and ...Bg7 for a double fianchetto in Hippopotamus style, which Boris Spassky used in his 1966 title match against Tigran Petrosian.

The direct 2. d4 Bb7 3. Bd3 f5 4. exf5 Bxg2 5. Qh5+ g6, catalogued as the Matovinsky Gambit, has been known to fail since Greco, who showed White winning after 6. fxg6. The Guatemala Defense, 2. d4 Ba6, was devised by Roberto Asturias and aims to exchange White's light-squared bishop immediately. Other named branches are mostly gambits: the Smith Gambit (2. d4 Bb7 3. Nf3), the Naselwaus Gambit (2. d4 Bb7 3. Bg5), the Wind Gambit (2. d4 Bb7 3. f3 e5) and the Hekili-Loa Gambit (2. d4 c5 3. dxc5 Nc6).

The name honors John Owen, an English vicar and strong amateur who used 1...b6 as his main defense and split two games with Paul Morphy in 1858. Isidor Gunsberg played it repeatedly in 1889. It was otherwise seldom seen at master level until Bent Larsen and Michael Basman took it up in the 1970s. Later exponents include Tony Miles, Nona Gaprindashvili and Blatny, and it has appeared in elite online blitz from Magnus Carlsen, Hikaru Nakamura and Alireza Firouzja. Its relatively thin theory makes it appealing as a surprise weapon against unprepared opponents.