Elton John delighted fans in LA on Saturday afternoon when he gave a surprise concert in the parking lot of the iconic Tower Records building on Sunset Boulevard. But that’s not all, as the singer also welcomed a very special guest to the stage, Lady GaGa, as the pair raised awareness for the Elton John AIDS foundation.

A photo posted by Lady Gaga (@ladygaga) on

Gaga announced the concert on twitter Saturday morning, when she told her followers: 'Get your asses to Sunset Blvd Tower Records! 12pm PT Elton John ft Me! Live on the streets of LA!’ The event was also live streamed for fans around the world by AOL.

The pair, who have performed together numerous times before including at the 2010 Grammys, sang a rendition of Elton’s classic ‘Don't Let the Sun Go Down on Me,’ with Gaga filling in for George Michael.

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After the show Elton wrote on instagram: “We shut down Sunset!!! Thank-you from the bottom of my heart to everyone who supported today's surprise gig. Massive thanks to the City of West Hollywood for supporting the Elton John AIDS Foundation.”

Aside from being sometime collaborators, Elton and Gaga are also close friends, as the songstress is godmother to Elton’s two sons Zachary, 5, and Elijah, 3.

Speaking about godmother Gaga during an appearance on 'The Talk' Friday, Elton said: "She buys them presents on their birthdays and at Christmas, but more than anything, which is the best thing, she's a good godmother.”

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"She comes and she bathes them, and she sings to them and she tells them stories, which is the best thing of all," he added. "It's the personal things."

"To do something and to give your time...it's easy to buy a present and send it round. She doesn't just do that, she comes round and spends time with the children and that's what I love about her.”

A photo posted by Elton John (@eltonjohn) on