Willie Nelson is blaming Utah's high altitude for forcing him to cut a performance near Salt Lake City short.
Nelson ended his show early at the USANA Amphitheatre in suburban West Valley City on Sunday night.
He later apologized in a statement posted to his Twitter and Facebook accounts. The 84-year-old country music legend explained: "The altitude got to me. I am feeling better now and headed for lower ground."
Nelson's publicist didn't immediately respond to a request for further comment Monday.
Nelson was forced to cancel several concerts earlier this year because of what his publicist said was a bad cold.