In this line , Sente pushed 9th file Pawn such an early stage of the game . Against this move , 2...P-9d seems very natural move . But this move lead an rough game .
after diagram 1
Against 2...P-9d , Sente advanced the game with same moves as without 2.P-9f P-9d .
Gote also drops his Bishop . How do the 9th Pawns give influence in a game ?
Here shows a line of Bishop promotion . Sente can select Bishop exchange line .
after diagram 2
9th file Pawns causes Sente's attack in 9th file .
This is very rough game ! So if you don't like such a game , you should play 2...K-6b instead of 2...P-9d .