Chess Opening Theory/1. e4/1...c5/2. Nf3/2...e6/3. d4/3...cxd4/4. Nxd4/4...Qb6

Kveinis variation B40 Sicilian defence → French Sicilian → 4. Nxd4 4...Qb6 · Kveinis variation The rare and razor-sharp Kveinis (or Kveinys) variation has often been considered inferior to other variations of the French Sicilian, but statistics show it scores the best of any of Black's turn four moves at the club level, and respectably well at grandmaster level, too. It is especially efficacious as a surprise weapon in blitz and bullet games. ...Qb6 pressures b2, White's knight on d4, and beyond it the weak f2 square. Much of the variation's club-level success comes from White underestimating ...Bc5, where Black stacks power against f2. For example, 5. c4? Bc5! and Black threatens to win the knight. 6. Be3 Nc6 (increases pressure on d4) 7. Nxc6? Bxe3 8. fxe3 Qxe3+ --. 5. Nc3 is the most common move in amateur databases, but leads to sharp positions where Black gets a strong attack. After 5...Bc5 6. Be3 Nc6, White must find 7. Na4, and the line continues 7...Qa5+ 8. c3 Bxd4 9. Bxd4 Nxd4 10. Qxd4 e5. Though the game is even by engine, Black has more practical success. (7. Nxc6?, as above, is a common mistake. Another trap is 7. Nb3?? Bxf2+ 8. Kd2 Qe3#.) 5. Nb3 is the main line. From here the knight is less of a target, and it controls c5 to deny Black ...Bc5. Many other lines are playable, including 5. Be3 Bc5 6. Na3! threatening Nc4. Generally Black finds the pawn on b2 is poisonous, though taking it often leads to sharp lines that may pose White practical difficulties. For instance, the most common line after 5. Be3 in the Lichess amateur database is 5...Qxb2?! 6. Nd2 Bb4?? 7. Rb1 Bxd2+ 8. Bxd2?? (needed was 8. Kxd2!) Qxd4 ---. History 4...Qb6 was a pet line of Aloyzas Kveinys (lt) (1962―2018), a Lithuanian International Master.e.g. Klovans v Kveinys, 1986. Chessgames.com It has been employed by strong grandmasters including Nigel Shorte.g. Polgar v Short, 1997. Chessgames.com and Judit Polgar.e.g. Nunn v Polgar, 1992. Chessgames.com Theory table References See also