With Eric Clapton sitting in on lead guitar, The Beatles sans John Lennon cut what was then George Harrison's premier writing effort. McCartney played piano during the initial recording and laid down his bass as an overdub.
If there were ever any doubt as to McCartney's role as a team player, it can be put to rest by listening to his bravura playing here. For the most part, he keeps his lines simple and tidy, but that isn't to say they aren't loaded with emotion.
Underpinning Harrison's terse chunka-chunk acoustic guitars during the verse and chorus sections, McCartney picks an economical pattern in the bridges that is sweet and vaguely joyous. And then it's back to the heavy.
A masterful piece of musicianship, befitting a classic song.