Chess Opening Theory/1. d4/1...Nf6/2. c4/2...e6/3. Nc3/3...Bb4/4. a3/4...Ba5/5. b4

=Sämisch Variation=

5. b4
White punished black's careless play and will win black's bishop. Black may hold on to it with /5...Bb6/, but White can still play '''6. c5'''.