Regular grooming keeps mats to a minimum and reduces the chances of a mat becoming solidly "packed." If the mat isn't solidly packed, removal is easier. Here's what you do:
2) Once the mat has been separated, brush through the area to remove the dead hair and then comb through it again to make sure you have removed the entire mat.
2) Try to separate the mat with your fingers and then work on the mat from which ever side allows you the best access.
3) To loosen the mat, you may have to use more detangler as you progress, and you may have to allow the oil to soak for a while before it does its job. Patience is a requisite for both you and your Lhasa when you are faced with removing a solidly-packed mat.
4) Alternate between separating the mat with your fingers and separating it with the end tooth of your comb.
5) Don't yank and pull because that hurts the dog, and if he gets fed up and refuses to cooperate, you've got a battle on your hands. Gentleness is the key if you intend to get rid of the mat without losing or damaging the coat and without hurting your Lhasa.
The best way to control mats is just not to let them happen. But, anyone who's had a Lhasa can tell you that's not possible unless you brush the dog constantly. Constant brushing is neither feasible nor desirable. I know someone who has such a "mat phobia" that she spends hours brushing her dogs each day. The problem is that her grooming technique isn't all that wonderful, and her constant brushing has done more harm than good to the coats.