Chris Martin has been a longtime supporter of the Global Citizen Festival. Over the weekend, the Coldplay singer was slated to once again curate the New York festival, but the rain-soaked fans who turned up to see headliners Post Malone, Jelly Roll and Rauw Alejandro got way more than they expected at the event aimed at encouraging world leaders to end extreme poverty.

On Saturday (Sept. 28), Martin teamed up with Ed Sheeran to perform a surprise mini acoustic set, with Sheeran taking the lead on a version of Coldplay’s 2000 breakthrough hit “Yellow” while strumming an acoustic guitar as a smiling Martin provided backup on an electric piano and hopped in on the second verse. “That’s enough of that,” Martin laughed as they quickly moved on to Sheeran’s 2017 chart-topping juggernaut “Shape of You,” giving the song a jumpy, uptempo makeover.

The surprise jam ended with both men on acoustic guitar for a spirited run through Coldplay’s 2008 jam “Viva La Vida” before pivoting to Sheeran singing his “Thinking of You” along to Martin’s jazzy piano backing. While Martin was scheduled to speak at the event in his role as curator, Sheeran was not an announced performer and the crowd cheered them on enthusiastically as the two men shared a wam hug before walking off the stage.

It was just one of many highlights at this weekend’s event, which also included BLACKPINK’s Lisa debuting the new song, “Moonlit Floor.”

Watch the performance and some rehearsal video below.