by Ken Rosenthal

Acta will be replaced by bench coach Jim Riggleman, as originally reported on FOX Saturday Baseball. The only question is when. It could be a matter of days.

The Nats have an off-day on Monday before starting a series at the Yankees on Tuesday. They return home on Friday to face the Blue Jays.

Acta, 40, was hired by the Nats in November of 2006. At the time he was the youngest active manager in the majors. He's gone 148-234 in two and a half seasons. The Nats have the league's worst record this season at 16-43.

Riggleman has managed for the Padres, Cubs and Mariners. The Nats added him as bench coach this past offseason. He went from bench coach to interim manager last season for the Mariners after John McLaren's firing last June.

Riggleman's record as a manager is 522-652.