with Bd3

After 1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3 d6, the move 5. Bd3 completes the textbook London arrangement, with Nbd2, c3 and h3 typically to follow. The drawback is that against the fianchetto the bishop on d3 has little scope, since the pawn on g6 shuts the b1–h7 diagonal. For that reason some players prefer 5. Be2, the other named branch, where the bishop stands more modestly but is less exposed. In the 5. Bd3 line the engine considers the position level. In Lichess games Black has scored noticeably better than White.

Black's usual answer, chosen in about two-thirds of games, is 5...O-O, after which the standard plans apply. Black either prepares ...e5 with ...Nbd7 and ...Re8 or strikes at the center with ...c5. The engine also rates 5...c5 and 5...Nbd7 highly; the latter keeps castling in reserve while preparing ...e5. A different approach is 5...Bg4, which pins the knight on f3 and may give up the bishop pair to reduce White's control of e5. Of these main replies, it is the one against which White's results are best.