Robin Thicke Backs Out of Celeb NHL All Star Game Honoring Alan

Robin Thicke was supposed to coach a team at the Celebrity Shootout Saturday ... part of the NHL All Star game honoring his dad, Alan Thicke, but he backed out at the last minute.

Robin was slated to coach his brother, 19-year-old Carter, in addition to Justin Bieber and others.

The singer pulled out Friday night, clearly because of the child custody war in which he's embroiled with Paula Patton.

Robin is not allowed to go near his son Julian for the time being, per judge's order. Robin insists the abuse claims lodged by Paula are bogus, and she had years to complain but chose now just to get back at him.