The eccentric star also wore a ginormous feathered headdress at one point, before she later draped it around her shoulder to reveal her classy up ‘do.

Tony, on the other hand, opted for a cream suit and striped tie for the performance, with the crooner smiling along and looking like he was enjoying every single minute.

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Gaga is known to flash the flesh on stage

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Singer kisses Tony Bennett on stage

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Eccentric singer wore a sheer dress for the performance

Incredible singing career aside, Gaga is also keen to break into the acting world it seems, with her recently bagging herself a part in American Horror Story.

Appearing at Comic-Con, screenwriter Ryan Murphy dished the dirt on Gaga’s upcoming part, without giving too much information away.

“When you work with someone like her, you sign up for something that is larger than life and I think that’s what you want,” the Glee creator told a packed crowd.

“Part of her role involves fashion. You want Lady Gaga to look a certain way. The designers have been coming out of the woodwork with looks for her.”

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Born This Way megastar dons feathered headdress on stage

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Gaga belts out the hits with Tony Bennett

Ryan, 49, revealed it was the singer who came to him for a part, which obviously he instantly accepted.

He recalled: “How it happened with Gaga is she wrote and said, ‘I love the show, would you consider putting me on it?’ And I wrote back, ‘Yes. CAPS CAPS…'”

“The best call ever is ‘Please wait for Gaga’, and she got on the phone and could not have been lovelier.”

But fans will know there’s very little space for lovely in Ryan’s scare-fest, which the chart-topper, who is engaged to Chicago Fire actor Taylor Kinney, is more than happy about.

Ryan added: “She said, ‘I want to be evil,’ and I said, ‘You came to the right place.'”