The Beach Boys stars Al Jardine and Bruce Johnston have their fears about band leader Brian Wilson's health as the group's reunion tour continues - because they're not sure how long the singer will be able to continue.
The two stars admit the "delicate" nature of the Good Vibrations singer's mental health issues means the tour rests on keeping Wilson healthy and happy.
Jardine tells Rolling Stone magazine, "He needs his creature comforts. He's so delicate - he's like a GPS machine or something; all the guidance features have to be calibrated perfectly.
"Otherwise, he can veer off somewhere. I don't want anything to happen to him. He's our leader".
And bandmate Johnston agrees, insisting Wilson is like an astronaut who has floated too far into space "Did you see (movie) 2001 (A Space Odyssey)? Remember Dave Bowman, the astronaut? That's how I see Brian. He's way up in space, floating around... Brian appears, then he disappears.
"In the film, Dave came back on a television screen and talked to his wife and said, 'I'm going to some incredible place', then he was gone.
"I see Brian that way. He's been chosen to do incredible things. We just have to wait for them.
"He probably has more things going (on) inside that head of his - whole records that he's made up there - but he's one of those guys that doesn't need to talk that much. I listen to him closely. I love having the chance to be around him".
And Johnston, who replaced Wilson in the Beach Boys when the hitmaker chose to stop touring in the mid 1960s, fears the reunion could be shortlived if the singersongwriter walks away.
He adds, "It's not going to last very long, he's not going to do 170 concerts a year. That's not who he is".