Lionel Richie Premieres 'We Are The World' Doc, Duets 'All Night Long' With Jon Batiste

Lionel Richie is still buzzing with the magic from "The Greatest Night In Pop" exactly 39 years later ... the legendary singer proved he can still bring the house down with today's fresh, young talent!!!

TMZ also obtained footage of LR performing a duet with Jon Batiste of his chart-topping track, "All Night Long," inside Delilah in West Hollywood.

Lionel introduced Jon and Andra Day to the stage ... and was enjoying the show until Jon played the opening keys of "All Night Long" and Lionel couldn't resist joining in ... can't have those TikTokers thinking JB came up with the track!!!

Jon spoke on the song being a beacon of togetherness and he and Lionel harmonized the 'Jambo Jumbo' together.

Later, Jon and Andra joined forces to belt out their version of "We Are the World" ... earning LR's approval!!! Good job, guys.

Netflix had its premiere for "The Greatest Night In Pop" at The Egyptian Theatre in Hollywood beforehand ... a doc that chronicles the backstory of 1985's megahit "We Are the World" ... the African charity megahit that became the fastest-selling single at the time.

The record boasted of virtually every superstar in music at the time ... Michael Jackson, Diana Ross, Stevie Wonder, Ray Charles -- you name it ... and goes into detail about how they were able to manage dozens of legends' egos and end up winning 4 Grammy awards.

More importantly, though ... this charitable effort raised tons of cash -- upwards of $60 mil toward fighting famine and hunger in Ethiopia. So, it was a success on all fronts.

Inside the premiere, Lionel joked about the differences between the film and music industry and got a hearty laugh from the crowd ... because it's probably true!!!