There was no reunion of Beatles' survivors, no slow dance down memory lane. This was straight ahead rock and roll, blasted in a tiny club and featuring a backing band that included Pink Floyd's David Gilmour.
"What better way to rock out the century?" McCartney said during a pre-concert statement to a roomful of journalists. "This is where it all began. For me, this is where the century is going to end, to play rock and roll."
And play he did, scorching through a set that included one Beatles' song, "I Saw Her Standing There," a few rock classics such as Elvis Presley's "All Shook Up," and new tunes from McCartney's new album, "Run Devil Run."
The show brought McCartney full circle, back home to Liverpool, the old, wind-swept industrial city along the Mersey River where all those years ago, he was in a band with John Lennon, George Harrison and Ringn Starr.
So what if the original Cavern has disappeared, torn down and its bricks sold off?
It didn't matter. This was still sacred musical ground, an intimate basement club across the street from the old Cavern, where the Beatles honed their skills for nearly 300 performances before leaving Liverpool and changing the musical world.
Back when they were just four lads with guitars, drums and a dream, the Beatles played during the day and the night.
They even played at lunchtime in a gritty club where the bricks were covered in sweat and an acrid smell wafted down from vegetable stalls.
Their manager, Brian Epstein, described the club as a cellar full of noise.
Last night, it was full of joy.
Seeing McCartney in exuberant form was uplifting, another sign he is rebuilding his life and career after the death last year of his wife, Linda.
In an interview earlier this month, McCartney said he'd expected to be together with his wife, "80 years old sitting on a porch on our rocking chairs." Instead, he said, he was "very, very lucky to have had 30 glorious years with her."
Now, he finds himself back in the rock and roll mix, even as British music moves into a dance club era where the stars are disc jockeys.
The crowd of around 300, a hand-picked collection of media, industry executives and 150 contest winners, soaked up every moment in the sweaty club. The show was also on the Internet, beamed to local fans at a nearby park, and later broadcast on radio.
"It was short and sweet," said 18-year-old Sarah Wynn, who attended the show with her 50-year-old mother, Frances.
"Oh, she's 21 now," the daughter said, beaming at her mother.
"We were hoping Ringo and George would be here," Frances Wynn said. "It would have been absolutely fabulous."
Still, it was terrific stuff.
"It was rock and roll, sweaty and great," said local musician Graham Hill.
The excitement built all day on the streets of Liverpool as the city prepared to receive rock royalty.
McCartney may no longer live here, but he never cut his ties to the city, staging concerts here, debuting a classical piece and serving as the patron to the internationally renowned school for performing arts.
His arrival in a private airplane was the stuff of front-page headlines in the afternoon paper. By early evening, a crowd of several hundred assembled in a light rain outside the Cavern.
"This is a dream come true," said Cathy Fullerton, a 44-year-old medical technician from Glasgow who was among those who'd won a ticket lottery. "We drove 5 1/2 hours through snow to get here, and we'll drive back again," Fullerton said. "There's something magical about it all, though. Paul was part of our time."
Roger Medcalf, a 34-year-old student from Liverpool, won two tickets and brought his 38-year-old sister Hilary to the show.
"It's like our son is coming home," Hilary Medcalf said. "Back to Liverpool. Back to his roots."
Is Paul the most popular Beatle?
"John is," Roger Medcalf said. "But Paul runs a close second."
Graham Riches, a 56-year-old from Bristol, brought along his 18-year-old son, Adam, to show the kid a bit of Beatlemania.
"He's part of my youth, really, I grew up with him," Graham Riches said.
"I do listen to the Beatles," Adam Riches said. "It's amazing really to think their music lasted this long."
Christine Garrity of London was overwhelmed that she was seeing "a living legend, one of the all-time greats."
Also waiting to get in were Steve McDonald, 43, and Ian Murdoch, 42, a couple of musicians who have forged their careers playing Beatles covers for a band named Ringer.
"It's a cliche, but it's really the soundtrack of your life," McDonald said.
"We're going on stage after Paul is finished," Murdoch said. "It's good for Paul to be our supporting act."
At the Beatles' Shop a few paces down from the Cavern, Steve Bailey couldn't wait to shoo out his last customer and lock up. Amid the clutter of old Beatles records, books, badges, key chains and photos, Bailey talked of his love for a group that he never saw perform live and his love for a city that makes him homesick every time he leaves.
"Everyone else is saying it's the most exciting thing to happen to Liverpool," said Bailey, a 36-year-old who has managed the shop for 10 years.
"Until he's on stage, I won't believe it. The whole thing will be like a big dream."
So how did Bailey like the concert?
When it was over, the shopkeeper was among the first out the door, waving a set list, breaking into a huge smile and shouting out, "Unbelievable!"