As Siobhan Magnus takes to the stage tonight on 'American Idol' this week,  she does so with the ringing endorsement of her old drama teacher.

Magnus has been a revelation on season 9 of Fox's hit show and is quietly gaining momentum, but this does not come as a surprise to those who knew her before this year's Boston auditions of the behemoth talent competition.

“Well, she’s got a lot of sides to her. She’s not the giddy little emotional kid up there onstage. America is getting to see that,” BHS drama club teacher Ed O’Toole told the Boston Herald.

The 19-year-old Irish American played parts in numerous Shakespeare productions while at BHS, and O’Toole was impressed at her range of talents.

“Singing or acting, Siobhan’s an instinctive performer,’’ he told the Herald “It’s like watching Willie Mays. She works hard but makes it look easy.’’

She will need all her instincts about her as the cauldron of pressure that is the knockout stages continue under the searing scrutiny on the American public.