One of the commonest issues that shows up on management and Leadership courses "I've recently been promoted out of my team into the Teams management role"
Boundary alert! This sort of promotion is usually on the back of a good business case, it however doesn't factor in the boundary resets that are required in order for your 'friends' within that network to adjust and also to prevent new reports seeing your actions skewed, and possible interpretations of favoritism.
Great short article from the Harvard Business Review on how to manage this....
Also take a look at our assertiveness course http://www.securebase-esr.com/3-key-areas/personal-effectiveness.html