Kanye West irritated Met Ball organisers by "screeching" through his performance.
The 'All of the Lights' rapper - who was accompanied to the star-studded annual Costume Institute Gala in New York City on Monday by his pregnant fiancée Kid Kardashian - was one of the musical stars who took the stage at the event, but left organisers and guests scratching their heads by playing several unfamiliar tracks from his new album.
Kanye, who was sporting a bejewelled mask, began his set after Blondie performed some of their most popular tracks, and "started screaming" according to one onlooker.
The source added to the New York Post newspaper: "He played all new tracks that no one knew from his new album, and none of the crowd favourites. His songs were basically screeching into the microphone."
Another guest suggested the controversial musician's strange performance would have not been part of the plan for the A-list event.
The reveller said: "Every minute of that gala is programmed, and Kanye went off-programme and played whatever he wanted."
The Metropolitan Museum of Art insisted, however, that there was no issue with the 'Mercy' rapper's performance.
A representative for the venue said: "We were thrilled to have Kanye perform."
Kanye, 35, was watched by a crowd of Hollywood's biggest names including Madonna, Anne Hathaway and Eddie Redmayne, but particularly impressed Kim, 32, by dedicating a track to her.
Introducing a new song, he said it was "an ode to Kim ... about how awesome she is."