Nimzo-Indian - Kmoch variation
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3
White pushes the queen's pawn to d4. Black develops the knight to f6. White moves the c-pawn to c4.
Black moves the king's pawn to e6. White develops the knight to c3. Black develops the dark-squared bishop to b4.
White advances the f-pawn to f3.