[Event "?"]  [Site "?"]  [Date "2017.05.21"]  [Round "?"]  [White "Tactics #51"]  [Black "   Igor Lutsko - Sheila Barth Berntsen Sahl, European Club Cup, 2007   "]  [Result "*"]  [SetUp "1"]  [FEN "4r1k1/pp3pp1/2p2np1/2b5/P7/3Q3P/1P2N1PK/R1BBq3 b - - 0 1"]  [PlyCount "23"]   {[pgndiagram] The most efficient way to win is} 1... Rxe2 (1... Qf1 {Is also  sufficient. The threat is Bg1+} 2. Qf3 Qxd1) 2. Bxe2 {More resillient defence}  (2. Qxe2 Ng4+ $1 {They key move. Black forces a mate} 3. Qxg4 (3. hxg4 Qh4#)  3... Bg1+ 4. Kh1 Bf2+ 5. Kh2 Qg1#) 2... Bg1+ (2... Ng4+ {Is not good now} 3.  hxg4 Qh4+ 4. Qh3) 3. Kh1 {[pgndiagram] And how does Black win now?} Ne4 $3 {  White is lost} 4. Qd8+ Kh7 5. Bf1 Bc5 {[pgndiagram]} (5... Qxf1 {Would be a  gross blunder} 6. Qh4+) 6. Be3 Ng3+ 7. Kh2 Nxf1+ 8. Kh1 Ng3+ 9. Kh2 Qxe3 10.  Qh4+ Nh5 {[pgndiagram] And Black has a winning endgame} 11. g4 Qe2+ 12. Kh1 Bd6  {Forces mate} *