Chess Opening Theory/1. d4/1...Nf6/2. c4/2...g6/3. Nc3/3...d5/4. cxd5/4...Nxd5/5. e4/5...Nxc3/6. bxc3/6...Bg7/7. Nf3/7...c5/8. Bb5

This check is an attempt to provoke concessions by Black who has three options now. Clearly the main move is 8...Nc6, which develops the knight on its best square but allows complications after 9.d5.

8...Bd7 9.Be2 leads to a slightly better position for White who profits from the fact that the pressure on d4 has been reduced for the moment.

8...Nd7 places the knight on a passive square. There will be no serious pressure against d4 now, and White should have the better chances thanks to his pawn centre.

8.Bb5+
This check is fine since Black cannot block with ...c6, and thus should play Nd7. If Black wants a dull, equal position with no dynamic energy, he can play Bd7. Black is fine here.