Willie Nelson is being forced to reschedule several of his shows. The 80-year-old has suffered a shoulder injury, and has been advised by his doctor to take some time off to recuperate.

The singer's canceled dates include a highly-anticipated appearance at Zac Brown's Southern Ground Festival on Saturday, Sept. 28 in Nashville. Nelson's last appearance was on Saturday, Sept. 21 at his annual Farm Aid concert.

No word on how or when Nelson suffered the injury. His next scheduled appearance is on Oct. 15 in Louisville, Ky. The date coincides with the release of his latest album, 'To All the Girls ...,' a collection of duets with some of his favorite female singers, including Miranda Lambert, Sheryl Crow, Dolly Parton, Loretta Lynn and several others.

The album is Nelson's third on Legacy Records, which is a division of Sony Music. “I’m really happy to be back home with Sony Music,” Nelson says. “We have been partners for many years; all the way back to Pamper Music and Tree Music. We share a great history, and I’m looking forward to many more years together.”

For concert updates, or to find more information about rescheduled events, click here.

'To All the Girls ... ' is available for pre-order here.