[Event "?"]  [Site "?"]  [Date "2017.06.30"]  [Round "?"]  [White "Tactics #64"]  [Black "   Popov - Ryumin, Moscow, 1935   "]  [Result "*"]  [SetUp "1"]  [FEN "r7/1bb2p1k/p1n2rpp/1p1q4/1PpP4/P3BNP1/3QBPKP/R2R4 b - - 0 1"]  [PlyCount "9"]   1... Rxf3 {[pgndiagram]This leads to a forced checkmate, or to serious  material gains for Black} 2. Bxf3   (2. Kg1 Nxd4 {Is also crushing soon}) 2...  Qxf3+ $3 3. Kxf3   (3. Kf1 {Is the only way to avoid immediate loss, but it is  clear that White's position is lost}) 3... Nxd4+ 4. Kg4 Bc8+ 5. Kh4 Nf3# {  [pgndiagram] And White gets mated.} *