Katy Perry and Calvin Harris have had a public spat on Twitter after he dropped out of supporting her on her UK tour at the last minute.
The Scottish singer and DJ claimed: "her team suddenly moved the goalposts, and I was to appear on stage with no production", and told fans: "trust me you would have been more disappointed SEEING the show than u are with me cancelling."
Katy replied: "Funny the goal post seems to be perfectly fine for [other artists]. It's fine, I'm used to you cancelling on me, it's become ur staple!"
Calvin, 27, who toured with Rihanna in Australia earlier this year, tried to keep the peace, apologising to Katy's fans and attempting to justify his actions.
He tweeted: "Her show is awesome, you'll all have an amazing time without me. (especially w/o me DJing on a cardboard box in front of a pink curtain)."
He added: "I am really sorry @katyperry I'm just upset because I really wanted to play but ur team made it impossible. We tried really hard to sort it out, but playing side of stage for 30 mins, it seemed pointless me even being there. Didn't intend to cause offence or upset anybody."
Calvin later claimed he had received angry messages on Twitter from Katy Perry fans.
He said: "The whole KP stuff shd never have been on twitter, I was trying 2 handle it pro behind the scenes but I wont let myself get ripped like that."
© Press Association