A judge has agreed to delay the start of Bill Cosby's sexual assault retrial to allow his new lawyers to get up to speed on the case.

Bill Cosby will be retried in November on charges he drugged and molested a woman more than a decade ago, after a jury failed to reach a verdict after deliberating for six days.

A judge will let only one other accuser testify at Bill Cosby's sexual assault trial to bolster charges that the actor drugged and molested a woman at his estate near Philadelphia.

US entertainer Bill Cosby's lawyers are set to argue that prosecutors are reaching back to the "casting couch" era to round up female accusers and build a "stale" sexual assault case against him.