Marcus Mumford is still stunned by his cameo appearance onstage with Bruce Springsteen and constantly relives the moment by watching the clip online.
The Mumford & Sons frontman, married to Hollywood actress Carey Mulligan, was invited by The Boss to join him during his encore of Hungry Heart at the Pinkpop Festival in Landgraaf, Netherlands in May (12).
And he's confessed he's still so starstruck by performing with one of his heroes, he can't stop watching a film of the show on video-hosting website YouTube.com.
Mumford tells The Sunday Times, "It was the best f**king day of my life - unbelievable. The Boss had watched our show, which I didn't know until the penultimate song, when I turned round and saw him in his Ray-Bans, nodding... We watched his set from behind the monitor desk, then, halfway through Hungry Heart, he nodded at us and waved us on stage.
"He grabbed me round the neck and shoved the microphone in my face. Have I watched the YouTube footage? Absolutely, from every single angle. I never watch our band, but I'll never stop watching that."