On Thanksgiving - November 28, 1974, Elton was joined at Madison Square Garden in New York City by a surprise guest.
This came after a bet that he made with John Lennon: If the former Beatle's Whatever Gets You Through The Night (which Elton played and sang on) reached #1 in the US charts, John would accompany his friend in concert.
Lennon didnn't expect this to be a hit, but kept his part of the bargain, coming onstage towards the end of the show to join Elton and his band in Whatever Gets You Through The Night.
Their second tune was Lucy in the Sky With Diamonds. Lennon introduced the third number as “a song by an old estranged fiancé of mine named Paul,” before launching into I Saw Her Standing There — acknowledging his former bandmate with the last song he ever played in concert.