Brad Pitt spent his 53rd birthday with old friends

The 'Moneyball' actor - who has kids Maddox, 15, Pax, 13, Zahara, 11, Shiloh, 10, and eightyear-old twins Knox and Vivienne with estranged wife Angelina Jolie, who he is divorcing celebrated the milestone on Sunday with a low-key meal. An insider said: "Brad Pitt spent his birthday enjoying a mellow dinner in with a few close, old friends. "Brad has been working hard on maintaining a low-profile and his plan is to stay out of the spotlight until his divorce and custody issues are finalised. "He was not interested in celebrating his birthday out at any hot restaurants." Brad has been granted supervised visits to his six kids since the brunette beauty filed for divorce in September, and he is not thought to have seen them on his birthday. The insider added to HollywoodLife.com: "Brad will not be doing anything that will interfere with his custody battle and does not want it to look like he is busy dating or partying. "His primary focus right now is working on himself and working on rebuilding his relationship with his kids." Earlier this month, it was claimed Brad's eldest sons, Maddox - who the 'Fury' actor was accused of striking during a row on board a private jet - and Pax were "refusing" to see him. LA Superior Court Judge Richard J. Burdge Jr. recently denied Brad's request to hold an emergency hearing to keep the details of the custody battle private. A source said: "The judge only denied the request for an emergency hearing and not the actual motion requesting that the case be sealed."A hearing will be held on January 17. In September, the former couple agreed to attend family therapy sessions as part of their temporary custody agreement.