Middlegame
White, to play, may wish to cope with Black playing 10...Nf4. He can do this by playing 10.g3, or by playing 10.Re1 so that if 10...Nf4 11.Bf1 will preserve the bishop (in this position an important defensive piece). Or maybe White will plough ahead with 10.c5, the key move on the Q-side.