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(TMZ) - Where there is love, Usher will BE THERE - or so he promised earlier this week at an L.A. bar during a pretty incredible karaoke rendition of the Jackson 5's "I'll Be There" ... and it was all caught on tape.

The song requires some pretty impressive falsetto - but Usher hit ALL the notes early Tuesday morning at Rock & Reilly's on the Sunset Strip... and the crowd loved every second of it, singing along the whole time.

Sources tell TMZ, Usher had been hanging out upstairs in a private area with friends throughout the night - but came down around 1am to show the bar how karaoke is REALLY done.

(It's a pretty ironic song choice - considering Usher was NOT there... at his stepson's funeral two weeks ago... though the singer never explained why.)

Nevertheless - tough act to follow. 

Check out the video:

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