Grammy bosses have confirmed the two legends will perform at the ceremony, but have stopped short of commenting on rumours suggesting the two old pals will reunite onstage for a song on music's big night.
Officials are merely stating: "Each will perform".
But McCartney and Starr, who will make his performance debut at the Grammys, will hit the stage together to collect the 2014 Recording Academy Lifetime Achievement Award for their work with the Fab Four.
Meanwhile, 2014 MusiCares Person of the Year honouree Carole King and Sara Bareilles will team up for a performance, and nominees Taylor Swift, Keith Urban, John Legend, Macklemore & Ryan Lewis and Kacey Musgraves have confirmed spots.
Macklemore & Ryan Lewis, who will also be making their debut at the Grammys, have seven nominations, including Album Of The Year and Best Rap Album for The Heist, and Song Of The Year for Same Love.
Kacey Musgraves and seven-time Grammy winner Taylor Swift are up for four awards each.
Previously announced performers include Daft Punk with Nile Rodgers, Pharrell Williams and Stevie Wonder; Kendrick Lamar; Lorde; Metallica and Lang Lang, Katy Perry and Robin Thicke and Chicago.
There will also be a "special performance" featuring country legends Merle Haggard, Kris Kristofferson, Willie Nelson and nominee Blake Shelton.
The 56th annual Grammy Awards will take place on 26 January.