Rapper Wiz Khalifa has hired top divorce lawyer Laura Wasser to fight his estranged wife Amber Rose for joint custody of their son Sebastian.

Model Rose filed divorce papers in a California court on Wednesday (24Sep14), two days after their date of separation.

She cited irreconcilable differences for the split and demanded full legal and physical custody of the one-year-old tot, but now Khalifa has hit back at the busty blonde's request and is seeking joint custody of Sebastian.

In legal papers obtained by Tmz.com, the Black and Yellow hitmaker agreed to pay Rose spousal support, which is reportedly worth more than $5,000 (£3,125) a month, as per a pre-nuptial agreement signed before their July, 2013 marriage.

The deal also allegedly grants Rose a lump sum payment in excess of $1 million (£625,000).

Khalifa has yet to speak publicly about the divorce, but Rose took to her Twitter.com blog on Thursday (25Sep14) to blast rumours alleging she had cheated on her husband, suggesting he was the one who was unfaithful.

She wrote, "Please stop with the fake stories. I would never ever ever cheat on my husband in a million years I think u guys know this... Unfortunately my now ex husband can't say the same...

"I'm devastated and crushed but my main focus is Sebastian. Thank u for all the support in this difficult time."

Wasser is also representing actress Melanie Griffith in her divorce from Antonio Banderas and reality Tv star Khloe Kardashian, who split from basketball player Lamar Odom last year (13).