“Brush Knee and Twist Step (搂膝拗步)” is useful in street combat.
It is a technique to go counterattack suddenly while in the situation of defending the opponent continuous attacks.
The trigger timing of the counterattack is a movement called “Brush Knee” (see Photo 1 below), and its posture to hit back is such that the ball bounces. With that reaction, the stance changes from the right leading to the left leading.
The direction to strike back is determined by the leading hand on the same side of the foot advancing the step, which means the left hand in the photograph. This angle is important. You should never straightly step forward in the front of the opponent.
If you change your stance angle related to the opponent while turning into an attack, it would be more difficult for the opponent to sense the penetration angle. See Photo 2 above for the final pose of “Brush Knee and Twist Step”.
You should practice to be able to use the skill “Brush Knee and Twist Step” for both the left and right in the same level.
When you practice a motion of “Brush Knee” in the form, you move largely. However, its motion becomes small in the actual battle.