Madonna and Guy Ritchie's custody battle over their son Rocco is "a power fight" between the pair.
Rocco, 15, walked out of Madonna's 'Rebel Heart' tour in December to stay with his father in London and Guy is said to have hired lawyers as he prepares for a custody fight with his ex but insiders claim the battle is due to their contentious relationship.
A source told PEOPLE: "This is far beyond a situation about Rocco - it's about a situation between Madonna and Guy. They don't have a good relationship; it's more of a power fight between them and if he can one-up her. This is the best way he can do it."
The 57-year-old singer and the 47-year-old director divorced in 2008 and the source added: "Prior to their divorce, [their relationship] was horrible."
It was recently claimed the final straw for the teenager was when Madonna - who also has children Lourdes, 19, David, 10, and Mercy, nine - confiscated his mobile phone because she thought it was interfering with his homework.
A source said: "Madonna is quite firm with Rocco and she took his phone from him when it interfered with his studies.
"She is stricter than Guy and Rocco doesn't like it. When she took the phone away, it pushed him over the edge."
Rocco is currently living with Guy, his wife Jacqui Ainsley and their three children, Rafael, four, Rivka, three, and Levi, 18 months, in the UK.