Watch Thom Yorke Join Portishead for 'The Rip' at Latitude Festival

Radiohead singer also performs 'Tomorrow's Modern Boxes' songs live for first time, debuts a pair of new tracks

Thom Yorke hinted that he'd be a surprise performer at this weekend's Latitude Festival, but the Radiohead singer had more in store for the Suffolk, England fest than just his first concert of 2015: Yorke appeared onstage during Portishead's Saturday set to join in on "The Rip" off the band's 2008 album Third.

The track, a "favorite" of Yorke's, was previously performed by Radiohead during the band's soundchecks in 2008, and Yorke and guitarist Jonny Greenwood later shared their acoustic rendition of "The Rip" on Radiohead's Dear Air Space. "It's dark as man. Definitely their best record, there's no doubt about that," Yorke said of Third following its release in 2008. "My favorite one is a song called 'The Rip' and then there's one at the end which sounds exactly like that old Seventies band Silver Apples - just mental." Radiohead drummer Phil Selway and Portishead drummer Geoff Barrow also play together on a charity soccer team.

In addition to the Portishead cameo, Yorke headlined his own set later in the evening, a performance that served as the live debut for many of the cuts off his 2014 solo LP Tomorrow's Modern Boxes. Although riddled by technical issues – it was his first full solo gig in nearly five years – Yorke still showcased "A Brain in a Bottle," "Truth Ray" and "Guess Again!" for the first time alongside The Eraser's "Harrowdown Hill" and "Black Swan" and his Atoms for Peace project's "Amok."

Yorke's packed set for 3,000 festivalgoers at the smaller iArena stage after midnight also reportedly featured a pair of new songs, although video of those tracks has not emerged. It's unclear whether the unreleased songs are destined for a Yorke solo venture or Radiohead's in-the-works follow-up to 2011's The King of Limbs.

At a small February 2010 solo performance, Yorke unveiled four songs – "Lotus Flower," "Give Up the Ghost," "Separator" and "The Daily Mail" – that were eventually released a year later on either The King of Limbs or its subsequent non-LP singles.