Alison Krauss

It was announced on Friday afternoon that Nelson would be taking a few days off per doctor's orders.

Live version of the Led Zeppelin classic is the duo's first official release in two and a half years.

Duo began their trek with a performance in Tulsa, Oklahoma.

The trek begins June 2.

Gov't Mule, the Avett Brothers and many other acts will appear on various dates.

The duo's March performance at Red Rocks will be available as a worldwide stream.

Led Zeppelin legend felt "exposed and vulnerable" as duet album ‘Raising Sand’ began to form.

"I still don’t know enough to stop in any respect," singer said of his continuing career.

Upcoming album will include a wide range of folk, blues and rock covers, plus one original.

Lead single "Can't Let Go' finds the duo covering Lucinda Williams.

Singer has gathered roughly "40 different instrumental ideas" for a new band studio project