Hilary Duff in custody battle

Actress/singer Hilary Duff's amicable divorce from her estranged husband Mike Comrie has been tested by his custody demands.

The So Yesterday hitmaker separated from the sports star last year (14), and she made the split official by filing divorce papers in February (15).

In the documents obtained by TMZ.com, Duff is seeking primary physical custody of three-year-old Luca, granting Comrie with visitation rights.

But, in new papers filed by Comrie, he is demanding joint custody of their son.

Custody of Luca is reportedly the only point of contention in the couple's divorce, as both Duff and Comrie have a prenuptial agreement.

The former couple married in 2010.