In his first of three New York City shows this week, Bob Mould gave fans a surprise nobody could have expected during his encore last night (Sept. 10) at the Bowery Ballroom. Ryan Adams joined the legendary rock star onstage to perform four Husker Du tracks, including 'Something I Learned Today' from 1984's 'Zen Arcade.' Check out fan-filmed footage of the performance above.

In addition to that song, Mould and Adams tore through renditions of 'I Apologize,' 'Celebrated Summer' and 'New Day Rising.' The night was peppered with solo material from Mould as well as songs from his Sugar and Husker days, but there's no question the addition of Adams onstage made for an unforgettable highlight.

This isn't the first time Adams and Mould have collaborated; in fact, it's not the first time this week. In a series of bizarre but funny promotional videos for Adams' latest LP, Mould is seen hanging out in the studios of Pax Am. Oh, and Adams is featured in Mould's latest music video for, 'The War.'

And all of that came after this recent tweet from Adams:

Mould is currently on the road in support of his latest solo release, 'Beauty & Ruin,' through November. Get his full tour schedule here. Adams is preparing for a trip to London for a series of gigs, including a stint at this year's iTunes Festival. You can follow along with his itinerary at his official website here.

As you wait for them to come to your hometown (maybe together again?), check out more fan-filmed footage of Mould and Adams rocking out last night, this time to 'I Apologize,' from 1985's 'New Day Rising':

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