While Week One of Coachella is often the most hyped, the second weekend can offer some surprises as well. For instance, The Replacements rocked out with Green Day's Billie Joe Armstrong joining them for much of their Coachella performance Friday night (April 18).

Billboard reports that Armstrong's addition was a welcome one as the band's frontman Paul Westerberg was suffering from back trouble and spent much of the set confined to a sofa while playing his guitar parts and singing.

The Green Day vocalist took the stage early in the set and rocked through a number of classics including 'Can't Hardly Wait,' 'Color Me Impressed,' 'Alex Chilton' and 'I.O.U.' Fan-shot footage of the latter song can be seen below.

Armstrong, a longtime fan of the band, mused, "Dreams really do come true," while he was later kidded by bassist Tommy Stinson, who remarked of his playing, "You'll get it Billie; It's in E like all the others." The set also included such standouts as 'I'm in Trouble' (seen above), 'Kiss Me on the Bus,' 'Tommy Gets His Tonsils Out' and 'I Don't Know.'

Even with Westerberg's injury, the second weekend performance proved to be a unique experience for those in attendance.

Watch Billie Joe Armstrong With The Replacements on 'I.O.U.'