Apparently, there's a reason Julian Casablancas + the Voidz is a side project. When the Strokes frontman decided to cover his main band's "Vision of Division" during their set at Barcelona's Primavera Sound Music Festival over the weekend, Strokes guitarist Albert Hammond Jr. was on hand to witness it – and one person in the crowd managed to catch Hammond's priceless reaction.

Check out the video below and jump to around 3:46 for the awkward moment (that's him on the left). The track from 2006's First Impressions of Earth is already pretty complex and dynamic, but the Voidz do their best to push it to its limits.

Hammond – who will release his third solo album, Momentary Masters, on July 31 – also performed at the festival in Spain; Momentary Masters will hit the streets via Vagrant.

It was a big week for Casablancas, though. He also relaunched his official website with a batch of new sections including "Politics" (in which he posts stories that will be "helpful in understanding our current world better") and "Master Mix Tapes" (in which he posts his essential playlists for the likes of Lou Reed and Bob Marley).

Julian Casablancas + the Voidz – "Vision of Division" at Primavera Sound