Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. d3

=Two Knights Defence 4. d3= If 4...Bc5, then this opening transposes to the Giuoco Pianissimo.

Theory table
.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.d3