Larsen's Opening is a chess opening starting with the move: It is named after the DanishgrandmasterBent Larsen. Larsen was inspired by the example of the great Latvian-Danish player and theoretician Aron Nimzowitsch, who often played 1.Nf3 followed by 2.b3, which is sometimes called the Nimzowitsch–Larsen Attack. It is classified under the A01 code in the Encyclopaedia of Chess Openings. The flank opening move 1.b3 prepares to fianchetto the where it will help control the central squares in hypermodern fashion and put useful pressure on Black's. The b2-bishop is often a source of recurring irritation for Black, who should not treat it lightly. Although Larsen was initially very successful with this opening, it suffered a setback in the 1970 USSR vs. Rest of the World match in Belgrade, where Larsen played it against reigning World ChampionBoris Spassky and lost in 17 moves. Larsen was also decisively defeated when playing it against Rosendo Balinas, Jr. at Manila in 1975. Notably, this opening received interest from Bobby Fischer the same year, who employed 1.b3 on at least five occasions, winning all five, including games with GMFilip, GM Mecking, GM Tukmakov, and GM Andersson. Today, Larsen's Opening is occasionally used at the GM-level, with top grandmaster Richárd Rapport employing it regularly and successfully. It was also employed at the 2018 Chess Olympiad by Baadur Jobava, in a game against Šarūnas Šulskis, which ended in defeat for the former.
Popularity
The move 1.b3 is less popular than 1.g3, which prepares a quick castling. According to ChessBase, 1.b3 ranks sixth in popularity out of the possible twenty first moves while the fifth-ranking 1.g3 is about three times as popular. Larsen frequently used unconventional openings of this sort. He believed it to be an advantage in that Black, usually unfamiliar with such openings, is forced to rely on his own abilities instead of relying on memorised, well-analysed moves of more common White openings.
Main lines
Black has several options to meet 1.b3. The most common are:
1...e5, the Modern Variation, is the most common response, making a grab for the centre and limiting the scope of the white bishop. Play typically continues 2.Bb2 Nc6. Then the Main line is 3.e3 d5 4.Bb5 Bd6 5.c4. After 2.Bb2 Nc6, 3.f4 is the Paschmann Gambit. After 2.Bb2, 2...f5 3.e4 is called the Ringelbach Gambit.
1...d5, the Classical Variation, is the second most common, also making a grab for the centre and preserving the option to fianchetto the king's bishop to oppose the white one. White can play 2.Nf3 to transpose to the A06 line, or 2.Bb2 to proceed in the A01 line.
1...Nf6, the Indian Variation, developing a piece and not committing to a particular pawn formation just yet. 2.Bb2 and if 2...g6 then 3.e4, taking advantage of the pinned knight. 3.g4 is called the Spike Variation
1...c5, the English Variation, retaining the options of...d5, or...d6 followed by...e5. 2.c4 transposing to an English Opening or 2.e4 transposing to a Sicilian Defence.
1...f5, the Dutch Variation. 2.Nf3.
Less common lines include:
1...e6, with Black setting up a variation on the French Defence. Here Keene recommends 2.e4 and if 2...d5 then 3.Bb2.
1...c6, a Caro–Kann variant preparing for...d5. Again Keene recommends 2.e4 and if 2...d5, 3.Bb2.
1...b6, the Symmetrical Variation, is completelyfine for Black.
1...b5, the Polish Variation.
1...Nc6, a variant of the Nimzowitsch Defence, with this move, Black aims to provide support for the advance of e-pawn. The most common sequence that Black applies is 2...e5 or less commonly 2...d5.
1.Nf3 Nf6 2.b3
1.Nf3 Nf6 2.b3 is a similar opening. Nimzowitsch preferred to make the knight move first. Black may play 2...d5 or 2...g6. After 2...d5, White usually plays 3.Bb2, then Black usually plays 3...e6.
After 2...g6, White can play 3.g3, 3.Bb2, or 3.c4. The move 3.g3 is the same as 2.g3 g6 3.b3, which gives Reti Opening or King's Indian, Fianchetto without c4. With move 3.Bb2, Black usually plays 3...Bg7. White can continue 4.g3, 4.c4, or 4.e3. After 3.c4, play usually continues 3...Bg7 4.Bb2.
Nimzowitsch–Larsen Attack
The opening 1.Nf3 d5 2.b3 is called the Nimzowitsch–Larsen Attack. It can be derived from 1.b3, but 1.Nf3 is more usual. Common replies for Black are 2...c5, 2...Nf6, and 2...Bg4. For each, White can play 3.Bb2 or 3.e3. 3.Bb2 can be followed by 4.e3.
