EXCLUSIVE: Another Oscar winner is joining the cast of HBO’s Luck. Mercedes Ruehl has come on board as a series regular for Season 2 of the horse racing drama starring Oscar winner Dustin Hoffman. She plays Julietta Caligari, the mother of Renzo (Ritchie Coster), a role she originates in an upcoming guest appearance on the series’ current freshman season. Luck, from Michael Mann and David Milch, is a behind-the-scenes look at the world of horse racing and gambling’s denizens – owners, trainers, jockeys and gamblers. Hoffman and Nick Nolte, nominated for an Oscar this year, lead the cast of the series, which received a 10-episode second-season pickup last week shortly after its official premiere. Ruehl is with Innovative and manager Craig Dorfman.