Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. Ng5/4...d5/5. exd5/5...b5/6. Bf1

Ulvestad variation C57 Two knights defence → Ulvestad variation 6. Bf1 6. Bf1! is a surprising move that un-develops the Bishop, but by guarding the g2 pawn with the bishop the threat of ...Qxd5 is nullified. Now if 6...Qxd5?!, White can calmly answer 7. Nc3 with tempo, and once Black's queen is driven from the a8-h1 diagonal, e.g. after 7...Qc5, White can then snap up the pawn after all, 8. Bxb5!, and Black has no threats. Though 6...Qxd5 may be off the table, Black's knight is still en prise and this must be resolved. Black may consider moving the knight instead. 6...Nd4 is the main move. The knight guards b5 and pressures important squares in White's position. White is best to shoo it away immediately, leading to a trade of knights: 7. c3 Nxd5 8. cxd4 Qxg5 9. Bxb5+ Kd8 +. White wins back the pawn and has a small edge. This is a transposition into the Fritz variation, where ...Nd4 is played on turn 5. Ulvestad's original analysis suggested 6...h6?!, a counterattack on White's knight that recognised that Black was better after either 7. Nf3? or 7. dxc6?.A New Move in an Old Defense Chess Review Ulvestad Olaf I. 1941 January 7-8 However, in 1963Kurkin v Mihaljcisin, 1963. Chessgames.com it was discovered that White can play 7. Nxf7! anyway, the Kurkin gambit, and after 7...Kxf7 8. dxc6 has run away with the pawns. Why not simply take the pawn back with the knight? 6...Nxd5, as played in Carlsen-Gukesh, 2024, is good and has become more popular in recent years.Gukesh v Carlsen, 2024. Chessgames.com Theory table 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 b5 6.Bf1 6 7 8 9 10 Bf1h6 Nxf7Kxf7 dxc6Bc5 Be2Rf8 += ...... Nf3Qxd5 Nc3Qe6 Bxb5Bb7 O-O += Fritz variationby transposition ...Nd4 c3Nxd5 ∞ ...Qxd5 Nc3Qc5 Bxb5Be7 Qf3Bd7 O-OO-O += ...Nxd5 Bxb5Bb7 Qf3Qxg5 Qxd5Qf6 Nc3 += ...Bg4 f3Nxd5 Nxf7Kxf7 fxg4Nf4 c3 += References Two Knights Defence