But not just any old friend - Sir Paul McCartney.
The music legend will perform the first concerts at Citi Field on July 17 and 18.
In a statement, McCartney says he's excited to be the first to play the stadium, and he's "really looking forward to a buzzing show."
The 66-year-old former Beatle was a surprise guest last summer for Billy Joel's concert at Shea Stadium. The previous home of the Mets - shut down to make way for Citi Field - was also where the Beatles performed for a sold-out crowd of screaming fans in 1965.
Copyright 2009 The Associated Press.