Lady Gaga treats Tony Bennett to a sweet birthday surprise

In case you didn't know it, Lady Gaga simply adores Tony Bennett.

The two really do make quite the dazzling duo. So when they hit Washington on Saturday night to perform the final concert of their sold-out, 7-month concert tour, Gaga wanted to do something special for him. With his birthday just days away -- he turns 89 on Monday -- she surprised him on stage with a birthday serenade and a ginormous cake.

Lady Gaga then led the entire audience in a singalong of Happy Birthday with everyone up on their feet. We were there, and it was cute, cute, cute!

Before the show, she shared her surprise on Instagram...knowing full well that while he is on social media, there was a good chance Tony wouldn't see it.

The cake, a creation of Charm City Cakes's Duff Goldman (yep, the Ace of Cakes guy), was based on the cake originally created for President John F. Kennedy’s birthday at which Marilyn Monroe famously sang Happy Birthday Mr. President. This version also featured the singers with their beloved pets.

The pair couldn't be any cuter, and we love how Tony calls her "Lady."

As for Gaga, she speaks very highly of him, and has loved their time together.

Also, we still can't get over the fact that he'll turn 89 on Monday. The man can still belt it out with the best of 'em!

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