Rapper Big Boi has challenged his estranged wife's demand for sole custody of their young son by filing for joint physical and legal care.

The Outkast star's spouse, Sherlita Patton, moved to end the pair's 11-year marriage last October (13), claiming their union was "irretrievably broken".

She asked to be granted full custody of Cross, but now Big Boi is fighting back, insisting the 12 year old would benefit from spending an equal amount of time with both his mum and dad.

The hip-hop star, real name Antwan Andre Patton, has also responded to Sherlita's demand for child and spousal support, declaring he is willing to pay whatever Georgia officials deem appropriate.

However, in his legal papers, the rapper has also suggested his ex make use of her good health and education and get a job so she won't have to rely on his funds alone, according to Tmz.com.

Cross is the former couple's only minor child - the Pattons are also parents to 18-year-old daughter Jordan.