He famously sang he left his heart in San Francisco.

And hopefully Tony Bennett had left his spectacles in his dressing room after Lady Gaga, 29, flaunted her derriere in a see-through dress as they performed together in Italy on Wednesday.

The 88-year-old’s heart would surely have been racing had he saw the chart star’s skimpy stage outfit from the rear.

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OId pro: Tony Bennett managed to resist the temptation to stare at Lady Gaga’s derriere during their performance in Italy on Wednesday

Thankfully the dynamic duo, who recorded the rather appropriately named Cheek to Cheek, managed to get through their show without Tony getting too distracted.

In fact, the Poker Face favourite managed to give her supporters plenty of thrills, as she ran the gamut of multiple costume changes during her performance.

Their show proved to be the highlight of the Umbria Jazz Festival in Perugia, and was completely sold-out.

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Gordon Bennett: Tony’s heart would surely have been racing if he caught a glimpse of Gaga from behind

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Poker Face: You would not have guessed she was wearing a risque outfit given the singer’s demeanour

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How appropriate: Perhaps Gaga was paying a subtle tribute to their Cheek to Cheek album with her outfit

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Age and beauty: Heartthrob Tony is looking incredible at the age of 88

Tony was forced to cancel the pair’s sold-out Royal Albert Hall hours before they were to take the stage last month.

Bennett, who fought as an infantry man in World War Two, apologised to his fans on Twitter and allayed rumours that he’d had a heart attack.

Gaga dazzled as she ended up playing a last-minute gig at the capital’s legendary jazz venue, Ronnie Scotts, wearing a typically outlandish ripped, fishnet bodystocking, complete with nipple pasties.

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Just Dance: The singer proved he can still move with the best of them as they jived together on stage

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It’s almost the end of the road: The pair will finish up their tour in Washington, DC on August 1

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Having a great time: The pop star seemed to enjoy sitting with the pianist as she performed another ditty

The pair will be performing in Spain on Thursday evening, before travelling to the United States for the rest of their tour, which ends in Washington, DC, on August 1. 

Gaga is also keeping her hand in pop culture, despite her diversion into the world of jazz.

The singer and actress stars in the upcoming season of the creepy FX show, as the upcoming season takes place in a spooky hotel.

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Red alert: This was just another in a long line of risque outfits worn by the eccentric star

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Dazzling the crowd: At one point Gaga flashed her ample cleavage in a sexy purple sequined number

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Feathering her nest: Gaga will be raking in the cash after the duo’s latest show was a complete sellout

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The only way is up: She bore a resemblance to much-treasured 80s popstrel Yazz in this outfit