The Dan Chi Sau is a basic in Wing Chun training, and it's important to execute it properly in order to progress to more advanced techniques.

To commence with Dan Chi training, it's crucial to note that starting with one arm is typical before progressing to two arms. This is where the single-arm Dan Chi sau comes into play as it serves as a straightforward format to advance to the double-arm version.

Firstly, establishing the connection between the bottom and top triangles of the body, with proper pelvic tilt and heel alignment, is vital. Once set, one can initiate the drill.

The Dan Chi Sau emphasizes maintaining a robust structure similar to a brick wall and linking the elbow to it. The real training involves learning to preserve this structure and the third spring from the forearm to the hand.

While practicing the Dan Chi Sau with a partner, one should meet in the middle and establish an airtight seal, akin to a boa constrictor gripping its prey. The first action is a palm strike, but it's essential to keep the elbow positioned and linked to the brick wall. Only the wrist should move.

When initiating the single-arm Dan Chi sau, using a frontal stance is crucial. One partner occupies the outer position, utilizing Folks out, while the other adopts the inner position, using Tan Sau. The outer partner will strike the inner partner with a palm strike, which is fundamental for comprehending defense against attacks.

However, it's crucial to note that the palm strike should be horizontal, not downward, as a downward strike can be both hazardous and ineffective. Executed correctly, the inner partner will use Jum Sau to defend, which involves slightly sinking the elbow while maintaining the centerline. One should avoid doing anything drastic like jut sau or pulling back, as this can be hazardous and bring the attacker closer.

After defending with Jum Sau, the inner partner follows up with a punch that turns the attacker's arm up into bong sau, a pivotal technique in Wing Chun. This punch is based on the theory of pressing the head, and then the tail rises, which implies that the punch causes the attacker's arm to rise, creating a clear path for the defender to strike.

It's vital to remember that executing the Dan Chi drill requires keeping the elbow low, and the fist should be in front of the attacker's chest, not their face. Punching with the fist in front of the attacker's face would create a ramp for the attacker to strike them in the head. Only use bong sau when the attacker gives a low elbow punch.

In conclusion, the single-arm Dan Chi sau is a crucial starting point for Wing Chun students to learn to defend and attack accurately. Proper execution of techniques is crucial to advance to more complex techniques successfully. With practice and patience, students can master this drill and refine their Wing Chun skills.