Black to play and win (hard)
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Show moves
1...Ba3+ 2.Kxa3 b4+! ( 2...Qc1+? 3.Bb2 b4+ 4.Ka4 Nb6+ 5.Kxb4 Rb5+ ( 5...Qe1+ 6.c3 ) 6.Kc3! ( 6.Ka3? Nc4+ ) ) 3.Ka4 ( 3.Kb2 bxc3+ 4.Ka3 Qc1+ 5.Ka4 Nb6+ 6.Kb4 a5+ 7.Kxc3 Rg3+‼ 8.hxg3 Qe3+ 9.Kb2 Nc4+ 10.bxc4 Rb8+ 11.Ka1 Qc1# ; 3.Bxb4 Qc1+ 4.Ka4 Nb6# ) 3...Nb6+ 4.Kxb4 Rb5+ 5.Ka3 Qc1+ 6.Bb2 Nc4+ 0-1
Games PGN
Created about 5 years ago. 
[Event "Halle"]
[Site "?"]
[Date "1967.??.??"]
[Round "?"]
[White "Zinn"]
[Black "Minev"]
[Result "0-1"]
[FEN "6rk/5p1p/p4P2/1pbn2r1/3P3R/1PB4Q/PKP2R1P/6q1 b - - 0 1"]
[SetUp "1"]

1...Ba3+ 2.Kxa3 b4+ $1 ( 2...Qc1+ $2 3.Bb2 b4+ 4.Ka4 Nb6+ 5.Kxb4 Rb5+ (
5...Qe1+ 6.c3 ) 6.Kc3 $1 ( 6.Ka3 $2 Nc4+ ) ) 3.Ka4 ( 3.Kb2 bxc3+ 4.Ka3 Qc1+
5.Ka4 Nb6+ 6.Kb4 a5+ 7.Kxc3 Rg3+ $3 8.hxg3 Qe3+ 9.Kb2 Nc4+ 10.bxc4 Rb8+
11.Ka1 Qc1# ) ( 3.Bxb4 Qc1+ 4.Ka4 Nb6# ) 3...Nb6+ 4.Kxb4 Rb5+ 5.Ka3 Qc1+
6.Bb2 Nc4+ 0-1