The normally-private couple put on a rare show of public affection as they joined TV producer friend Lorne Michaels and actor Jack Nicholson at the baseball in New York City last night.
McCartney and Shevell were kissing and cuddling in the front row as they watched her home team New York Yankees defeats the Texas Rangers 9-2 at Yankee Stadium in the Bronx.
Take me out to the ballgame: Self-confessed New York Yankees fan Sir Paul McCartney and girlfriend Nancy Shevell watch the team play the Texas Rangers at Yankee Stadium in the Bronx
The foursome were seated in the coveted 'Legends Seating' area right behind the home plate, where tickets sell from anything between $525 to $2,625 a person.
Towards the end of the game, Shevell, 47, slipped off early, leaving her boyfriend of nearly two years with his male companions.
The 67-year-old politely stood up with his American lover and friends as they listened to patriotic song God Bless America during the seventh inning.
In between innings, the quartet drank beers, munched on hot dogs and swapped notes on the players.
Kiss me quick: McCartney gives me a kiss as Shevell leaves the stadium
McCartney was introduced to the popular American game several years before he met divorcee Shevell in October 2007, after his high-profile split from Mills.
Saturday Night Live producer Michaels - who was seated next to McCartney last night - brought the Beatles legend to his first baseball game.
In a recent interview with the Boston Herald, McCartney said: 'Lorne Michaels took me to my first game years ago. It was a Yankees game, so I became a Yankees fan.'
Noting baseball similarity to rounders, McCartney insisted he would be staying firmly off the pitch after an unfortunate incident with a bat as a child.
Patriots: Jack Nicholson, TV producer Lorne Michaels, McCartney and Shevell stand to hear God Bless America
He said: 'Baseball to us (Brits) is a game called rounders we played as kids.
'Actually, I accidentally broke a girl’s nose when I was a kid with my back swing. I still remember her name. Shirley Prytherch. P-r-y-t-h-e-r, um, c-h, I think. I don’t know, but it sounds Welsh to me.
'It’s something like this that accounts for all the armour you guys wear now playing baseball. She didn’t have any and look what happened to her.'
Meanwhile, McCartney admitted frequent rumours about his death had become an 'occupational hazard' for his life as a famous rocker.
Home run! McCartney and Shevell react after the Yankees score a home run
The singer recalled a conspiracy theory in October 1969 in which a Michigan DJ claimed his bandmates John Lennon, Ringo Starr and George Harrison had recruited a lookalike McCartney to stand in for him after he 'died' in 1966.
The DJ believed the shot of McCartney on the front cover of the group's 1969 Abbey Road album wasn't the singer and the bare feet was a code to mean a corpse.
McCartney tells Mojo magazine: 'It was funny, really. But ridiculous. It's an occupational hazard: people make up a story and then you find yourself having to deal with this fictitious stuff.
'I think the worst thing that happened was that I could see people sort of looking at me more closely: "Were his ears always like that?" It was madness.'
Man on the match: Batter Jorge Posada scored three home runs last night
