SIR Elton John is worried about next year's (07) memorial concert for DIANA, Princess Of Wales, because it will be a "very emotional day" for him. John is preparing to sing CANDLE IN THE WIND at the event. It would mark the first time he has performed it since the British royal's funeral service in September 1997. Other acts scheduled to perform include Joss Stone, Duran Duran and Bryan Ferry. John told London radio station Heart FM, "It will be a very emotional day for me, very emotional. "There might be a role for me doing the MC bit and linking it all together. It's going to be fun. "We'll probably get a few more acts to do it too. It's the princes' choice of acts and if I can help them co-ordinate it I will because I'm used to that sort of thing."