How to defend on the breakdown:
The Assist Tackle- Hit the opponent around the ball to stop the offload and control the contact.
Attack the ball to turn over, to disrupt- Get in to where the tackle is made to give yourself a good opportunity to get the ball before the support comes.
If you decide you are going to go for the ball you must be 100% committed to it. Get a wide base and make sure you are low, tight and strong to prepare for opponents and expect contact.
To not commit- If there are support players, it is a waste of time to commit to the ball. You are more effective preparing for the next tackle.