Chess Board
[ECO code C19]
Advance Var. - The Smyslov Variation

Black's KKt to K2(e7) for ..Kt-B4 also enabled ..0-0.
White moves his Queen's Rook's Pawn on from QR3(a3) to QR4(a4) taking control of QKt5(b5) and opening a Q-side path for his QB. W-Alt.
    White  Black	White  Black
 1. P-K4   P-K3	     6.	PxB    Kt-K2
 2. P-Q4   P-Q4	     7.	P-QR4	    
 3. Kt-QB3 B-Kt
 4. P-K5   P-QB4
 5. P-QR3  BxKt ch

Example ends: Undo or Jump or Clear