Willie Dixon was one of the greatest bluesmen who ever lived. He wrote a bunch of the old blues greats, including Hoochie Coochie Man. He was a gold glove boxer, and Joe Lewis' sparing partner. He fought - and won - copyright violations for a bunch of his songs, most notably Led Zeppelin who stole his song You Need Love, turning it into Whole Lotta Love*.
And each of these bands had one of his songs on their debut album: Cream, Jeff Beck, The Doors, Led Zeppelin, The Rolling Stones, and Steppenwolf. Yowser.
This song showcases his virtuoso playing and soulful way of singing. It's quite a performance.
* Robert Plant admitted this after the lawsuit was settled in the late 1980s.