American singer Josh Groban is in concert in Sydney, Melbourne and Brisbane. Pictured at Warner Music in Sydney.

The Muppets femme fatale revealed last year she had dated the operatic singer after they were set up by her ex, Kermit.

But the loved-up Groban has had enough of Miss Piggy riding his romantic coat-tails now he is in a committed relationship with Two Broke Girls star Kat Dennings.

“This was news nine months ago in the US and it was all I was talking about,” a mock furious Groban says. “She’s now brought this torrid affair into the media which I can only imagine is for her own self-promotion,” he says. “She was very difficult, very difficult.”

Groban is a triple threat with a self-deprecating charm that sucks you in, even if you aren’t partial to his kind of music. Wrapping those golden vocal cords around opera, American standards and Broadway classics has resulted in sales of 25 million records and thousands of concert tickets around the world.

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Committed: Singer Josh Groban and girlfriend Kat Dennings arrive for the Clive Davis & The Recording Academy's 2016 Pre-Grammy Gala. Picture: AFP / Mark RalstonSource:AFP

His comedic flair and natural acting chops have translated into roles in film and television from his breakthrough on TV drama Ally McBeal in 2001 through to 2014 movie Muppets Most Wanted. He did the junket rounds at the annual Sundance Film Festival in January for The Hollars, the directorial debut of John Krasinksi, which features an ensemble cast including the director, Anna Kendrick, Sharlto Kopley, Richard Jenkins and Mary Kay Place.

And now he can tick theatre off his list. Just before Christmas and months after he released his tribute to musical theatre with his Stages album, he revealed he had finally achieved his dream to star on Broadway.

Groban has signed on to play the lead in Natasha, Pierre and the Great Comet of 1812 which hits New York’s famed theatre precinct this year after a successful off-Broadway run.

He has been lobbying for the right role in musical theatre since his introduction via television — it is what he always wanted since cutting his teeth on high school productions — and last year’s Stages record served as a superfluous audition.

Ever since Groban stood beside Celine Dion as last minute replacement for Andrea Bocelli to sing The Prayer at rehearsals for the 1998 Grammy Awards, his ambitions have soared as high as his preternatural voice.

He stayed patient, looking for a role which suited him rather than risk being compared to all those who had gone before him in a perennial favourite, and fate appeared to be at work when it came to securing the lead of Pierre.

After seeing the off-Broadway production, he asked his agent to reach out to the producers just as they were contacting his agent to seek his interest in the musical.

“I’ve been dipping my toes in musical theatre for a very long time and never more so than with the Stages album,” Groban says. “I didn’t want to play the 57th Phantom Of The Opera, maybe the 58th but I don’t want to do it now.

“To have a new show and really pass the test is a great challenge and something I think will be fun.”

He will start rehearsals for the show after his Stages shows in Australia in April. His fans here may get a preview of his accordion skills as Groban has been learning the instrument for the play. Groban admits to a deep affection for the squeeze box.

Two of a kind: Like Weird Al Yankovic, Josh Groban is a squeezebox fan.Source:Supplied

“It feels like part of my body now and I understand the thrill Weird Al Yankovic has had his whole life having felt this beautiful squeeze box against my chest every day,” he says.

“I get drunk and practise it every day; for whatever reason I play the accordion better after a little whiskey, you need to relax into it.

“Plus my character is a raging alcoholic.”

His Australian fans may also wonder if Groban has belatedly embraced his inner hipster as he will be sporting a beard during the tour as part of his preparation for his Broadway debut,

“Pierre has to be pretty Rasputin looking. I like it, simple as that,” he says.

The singer and actor professes to be allergic to having days off, juggling his Sundance duties, Broadway preparations, working on songs for his next album and the upcoming tour of Australia.

“I like being scared. When you are tackling a lot of different things, you have to do a lot of planning so your muscle memory is ready to go,” he says.

Multi-talented Josh Groban arrives on the red carpet during the 58th Annual Grammy Music Awards in Los Angeles. AFP / Valerie MaconSource:AFP

SEE:Josh Groban, Concert Hall, Sydney Opera House, April 19, 20, 22, 23. $132.50 — $183.50. livenation.com.au

SEE:Josh Groban, Palais Theatre, St Kilda, April 25. $132.38 — $183.36. livenation.com.au

SEE:Josh Groban, Brisbane Convention and Exhibition Centre, April 28. $101.85 — $152.82. livenation.com.au