Matthew McConaughey was told his 'Mud' co-star Sam Shepherd had died when he was interviewed on a red carpet

Taken aback, Matthew said, "Sam Shepard moved on? Gosh damnit, from what?" before the reporter repeated the news and quizzed him for his fond memories of his late friend.

The actor admitted he was unprepared, but praised Sam for his captivating talent in their movie, which followed a pair of Arkansas boys, who help a fugitive called Mud - who is played by McConaughey.

Speaking of Sam - who starred as Mud's father-figure Tom in the movie

- he said: "Look, I'm not going to trivialise that situation - I just heard about it for the first time.

"But I always told (director) Jeff Nichols this - in 'Mud', the whole trailer for 'Mud' could be Sam Shepard sitting in that green chair telling the boy about who Mud is. It would be about a two-and-a-half minute trailer, but it would have been really badass."

And after the news sunk in, he added: "He moved on today? Damn, we lost one of the great ones. Great writer, great mind. Alright, see you in the next one, Sam."

Sam's family announced on Monday (31.07.17) that the Oscar-nominated actor died at home in Kentucky from complications pertaining to ALS (Lou Gehrig's disease).

His friend Patti Smith paid tribute to him in a lengthy letter in The New Yorker, in which she says he knew he didn't have much time left.

She said: "Sam promised me that one day he'd show me the landscape of the Southwest, for though well-travelled, I'd not seen much of our own country.

"But Sam was dealt a whole other hand, stricken with a debilitating affliction. He eventually stopped picking up and leaving. From then on, I visited him, and we read and talked, but mostly we worked.

Laboring over his last manuscript, he courageously summoned a reservoir of mental stamina, facing each challenge that fate apportioned him.

"Going over a passage describing the Western landscape, he suddenly looked up and said, 'I'm sorry I can't take you there.' I just smiled, for somehow he had already done just that. Without a word, eyes closed, we tramped through the American desert that rolled out a carpet of many colors--saffron dust, then russet, even the color of green glass, golden greens, and then, suddenly, an almost inhuman blue. Blue sand, I said, filled with wonder. Blue everything, he said, and the songs we sang had a color of their own."