NEW YORK Paul McCartney likes to get out of the Beatle bubble he's lived in since he was 21 and just be a regular bloke. So he does. No disguises, no bodyguards. Just Paul.

Sometimes he goes bowling. Or does the grocery shopping. Or goes to movies with his girlfriend and gets shushed by strangers for talking too much. A couple of years ago, he recalls, he found himself on a New York City bus ("Luckily, I had the right change"). Or rather, New Yorkers found him on the bus.

Everyone stared as the famous passenger took his seat, but no one said a word. Finally, someone -- "it was the African American lady" -- spoke up. " 'Hey!' " McCartney imitates, his voice rising, his delight at the memory evident. " 'Is you Paul McCartney?' "

" 'Yeah, I am!' " Sir Paul answered. "I'm in their face. I don't shrink away. No point. I'm from Liverpool, you've just got to get with it.

"So I said, 'Look, honey. Don't shout across the bus. Come and sit here!' "

The woman accepted the offer and the unlikely couple had a merry chat for several more blocks. And then the world's most celebrated songwriter reached his stop and melted into midtown Manhattan.

McCartney will play in front of 60,000-plus people at FedEx Field on Saturday, the third stop on his summer mini-tour and a milestone of sorts (the concert comes 45 years after the Beatles made their American concert debut in Washington, at the long-gone Coliseum). He'll be surrounded by the usual rock-god trappings and airtight security. But he says he savors encounters like the one on the bus because they remind him of who he was and where he came from before he and a few of his friends got together and revolutionized popular music.

"It grounds you, you know," McCartney says. "It's a balance thing. I'm just one of the people on the bus. I'm the famous one, but I'm behaving normally. . . . Really, it's important."

McCartney is telling this story a few hours before taking the stage for a sold-out show at Citi Field, the gleaming new home of the New York Mets. He's in his sound-check casual duds this afternoon -- basic white shirt with tiny dots tucked beltless into dad jeans, set off by some comfy black sneakers. He's ensconced in the ballpark's visitor's clubhouse, which has been retrofitted for its royal guest. McCartney's inner sanctum is all drapey curtains and plush couches, with low lighting and some kind of incense burning on the coffee table. "All right if I chomp?" asks McCartney, a vegetarian since the 1970s, as he stuffs a snack of grapes and almonds in his mouth.

For an official senior citizen -- impossibly, he's now 67 -- McCartney looks remarkably youthful. He's slim, almost slight, and truth be told, could even stand a few more pounds. The famously cherubic face is fleshier and lined just enough to remind you that McCartney isn't 21 anymore. The tousled hair is a flat brown. This is reassuring; who wants a Beatle, particularly the doe-eyed, ever-boyish Paul, to seem old or even to age at all?

The even better news is that McCartney's voice remains as strong and supple as it was in his youth, even in this, his 50th year of performing. Critics generally applauded the vocals and writing on his last album, "Electric Arguments," released last year under his Fireman alter ego. But McCartney is a revelation in concert. He plays straight through for about 2 1/2 hours each night, offering more than 30 tunes from his vast catalog. The set list ranges from such sweetly sung classics as "Blackbird" and the inevitable "Yesterday" to the frantic, voice-shredding chestnut "I'm Down." (On this day, even his sound check is a mini-concert, featuring a dozen or more songs, including a lovely version of "Midnight Special.")

McCartney's show also has several nods to souls departed; "My Love" is dedicated to his late wife Linda, "Give Peace a Chance" goes out to John Lennon, and "Something" is sung in honor of its creator, George Harrison. A nice touch: McCartney plays the latter song on a ukulele that Harrison gave him.