Willie Nelson is getting ready to release 153rd album, Last Leaf On The Tree. On Friday (Oct. 11), the 91-year-old songwriting legend joined Chris Stapleton during the country musician’s Austin City Limits set for two songs.

The pair performed “Whiskey River,” which they also did last year at Nelson’s Rock And Roll Hall Of Fame induction ceremony. They followed it with a duet of “Bloody Mary Morning.”

On Oct. 17, Nelson is headlining Austin City Limits’ Birthday Bash at the Long Center lawn. Watch his surprise appearance during Stapleton’s set below.

Last Leaf On The Tree is out 11/1 on Sony.