The second supporting player who reaches the breakdown (now a ruck if there is contact over the ball) must come in consciously straight (through the gate) and with the option to either support and clean out or to play the ball immediately using a pass. Making the right decision here is essential. If the player commits to the ruck without a scrumhalf present, they risk exposing the ball to the opposition.
If they hold off and try to play the ball in the face of a counter-ruck, they may be swamped by defenders coming through the gate. This decision-making process is covered later in the article.
Assuming the first supporting player has a strong body position and can deter counter-rucks, the second supporting player should come in from behind and clamp onto the first man. The collective strength of this position allows the ruck and possession of the ball to be secured, potentially without contest.