Elton Johnny.

Elton unveils rare footage of his 1974 performance in New York with John Lennon.

John Lennon's last public performance took place on Thanksgiving, November 28th, 1974, when he joined Elton John at Madison Square Garden in New York. His appearance was the result of a lost bet he made earlier in the year with Elton when he agreed to take part in the show if his song, "Whatever Gets You Through the Night" -- which Elton sang on -- went to number-one, which it did. Lennon came on to sing "I Saw Her Standing There," "Lucy in the Sky With Diamonds" and "Whatever Gets You Through the Night." After the show, Elton had a surprise waiting backstage for John -- his estranged wife, Yoko Ono, who attended the show with the owner of an art gallery. Within days, the couple reconciled -- and just over 10 months later, their son Sean was born.

Now, 38 years later, Elton has unveiled footage from that show, which he is projecting on the video screens as he does his tribute to Lennon, "Empty Garden," during his Million Dollar Piano shows in Las Vegas. The restored film, shot on Super 8 by a fan, Mary Ann Summers of New Jersey, is the only known color footage of the performance. She says, "When Elton began his introduction of John, we were all 'Yes! Yes! Yes!' It was for real! I simply can't describe the atmosphere -- 20,000 people in a place of pure happiness."