Many of today's top artists have gathered to honour The Beatles' legacy, with Sir Paul McCartney and Ringo Starr in attendance at the special concert.
"We are honouring the most important band of all time, and trying to do justice to their song while two of them sit there," Brad said in an interview before his performance.
"We know, going in, we're not going to sing like them, and we're going to try to do our own thing with it. But ... there's reasons why people get blasted when they cover Beatles songs in any situation. But here we are, we're all doing that tonight. So, I guess it's an even playing field in that sense."
When Sir Paul and Ringo took to the stage they turned what had been a fairly sedate affair into an arm-in-arm sing-along of hits Hey, Jude, Sgt Pepper and Yellow Submarine.
The telecast will air on February 9 on CBS, 50 years after The Fab Four made their first appearance in front of an American TV audience on The Ed Sullivan Show. It was a historic moment with more than 73 million Americans tuning in, changing pop culture in profound ways.
Even so, Sir Paul told the crowd he was hesitant to agree to commemorate it.
"What can I say about this evening, it's just amazing," he said.
"At first when I was asked to do the show, I was wondering if it was the right thing to do. Was it seemly to tribute yourself? But I saw a couple of American guys who said to me, 'You don't understand the impact of that appearance on the show on America.' I didn't realise that."
Grammy producer Ken Ehrlich said the tribute event was more than a decade in the making and was produced at the Los Angeles Convention Centre with archival footage from the band's Ed Sullivan era as well as their psychedelic and hirsute, hipster periods.
Maroon 5 kicked off the show by re-creating the opening moments of the 1964, appearance with All My Loving, then Ticket To Ride.