I remember when the Doobies appeared to connect with The Isley Brothers around 73. The Doobies released a track from 3+3 as a single, Listen to the music, and, sacrilegious as it may seem to say so, the Doobies did a better version of it.
Their next hit in the UK was another old Isley's song from the 60's Take me in your arms [rock me a little while], although I have to say that I do think that The Isley's did a better job of the latter song.