Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. Nf3/3...Nf6

=Slav Defence=

3...Nf6
Moves: 1. d4 d5 2. c4 c6 3. Nf3 Nf6

Black plays the natural developing move Nf6, which is invariably the best square for the black knight in the Slav. On f6, the knight exerts control over the e4 square as well as re-inforcing protection of the d5 square.

Theory table
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1.d4 d5 2.c4 c6 3.Nf3 Nf6