Acclaimed Britishblues singer Joe Cocker made his return to the albums chart with Fire It Up, his first new material in almost three years and his 23rd studio album, which ended the week at number 17.
American blues has held a fascination for British rock bands ever since Mick Jagger, Keith Richards and Eric Clapton heard their first Muddy Waters and Howlin' Wolf records.
Williams has had one game since post-British and Irish Lions tour shoulder surgery - for Cardiff Blues against Ospreys - but is expected to take on fellow world-class openside Richie McCaw at the Millennium Stadium on Saturday.
In the sixties, British bands like Led Zeppelin and the Rolling Stones mined American blues, first copying their heroes and then creating something vivid and novel.
The Blues approached Welsh rivals the Ospreys to enquire about the availability of Wales and British and Irish Lions star James Hook but the enquiry was rejected.
The trio gained places in the Blues senior squad, then Wales honours, and in Roberts' case became British and Irish Lions man of the series last year in South Africa.