What is the Led Zeppelin song that talks about squeezing a lemon that is NOT 'The Lemon Song'?

I keep hearing this really cool song on the radio, and I can't find out what the name of it is because the stupid DJs don't tell you the names of songs anymore. It kind of sounds like a medley, and near the end they go into 'The Lemon Song'. If anyone knows this would be great! Thanks!