Sir Elton John will step into the breach and perform at his Aids fundraiser after singer Lily Allen pulled out due to illness.
Pregnant Allen is unable to take to the stage as she has a viral infection, but can not take medication due to her condition, a spokesman for the event said.
Instead, Sir Elton will treat guests to a 45-minute set at the Grey Goose Character & Cocktails Elton John Aids Foundation winter ball on Saturday.
The spokesman said: "Lily Allen is a keen supporter of the charity and Grey Goose and is sorry that she is no longer able to perform live on the night.
"Lily Allen regrets that she has had to pull out of her scheduled appearance due to a viral infection.
"As Lily is pregnant and not able to take medication, she has been advised to rest until the infection clears. She apologises to Elton and to anyone attending the event."
The evening will include a cocktail reception, dinner by chef Marcus Wareing and an auction to raise funds for the charity.
Sir Elton will perform a selection of his hits, plus some new tracks from his latest album The Union with Leon Russell.
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