This is from the GM Sethuraman - GM Bruzon game from the St Louis Fall Chess Classic!
It is black to move in both positions. Can black win this?
Black to move and win (first puzzle)
1...Nd6!!, 2. f6 Kb2, 3. Kxc7 Ne8+!, 4. Kc6 Nxf6, 5. Nd2 Kc3!, 6. Nb1+ Kb4!, 7. Kd6 Ne4+!, 8. Ke6 Nc3!, 9. Nd2 a3 and Black wins
1...Nd6!!!, 2. f6 Kb2, 3. Nd2 a3!, 4. f7 Nxf7, 5. Nc4+ Kb3, 6. Nxa3 Kxa3, 7. Kxc7 h5!, 8. h4 Ne5, 9. Kd6 Nf3, 10. Ke6 Nxh4, 11. Kf6 Ng6!, 12. Kg5 h4!, 13. Kg4 Kb3 - Black King is ready to march to f6 and Black wins!!
Lazaro Bruzon Batista made a mistake with Nf6+?. He missed a winning move 1...Nd6!!!