Prosecutors have asked Judge Susan Garsh to step aside, saying she and prosecutor William McCauley have a "history of antagonism" stemming from a 2010 murder trial. McCauley won a conviction but criticized her in the media. He says Garsh was hostile and wrongly excluded evidence.
Hernandez's attorneys say in a filing the bias charges are unsupported and the recusal request is "patently without merit."
A Monday hearing is scheduled.
Hernandez has pleaded not guilty to murder in Odin Lloyd's killing.
A spokesman for prosecutors says an identical motion was filed two years ago and that Garsh gave the case to another judge.