Zukertort Opening: Black Mustang Defense
ECO A04
Move order
1. Nf3 Nc6
Ideas
ECO A covers irregular and flank openings—systems that skip the main e4/d4 fight early. White develops a knight and keeps flexible transpositions into d4 or c4 setups. This entry names the opening after the first moves. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.