Singer Cheryl Tweedy from pop band Girls Aloud punched a toilet attendant over a handful of lollipops and called her a black bitch, a court has heard.
Cheryl Tweedy denies the charges
The 20-year-old star is accused of racially aggravated assault occasioning actually bodily harm on Sophie Amogbokpa, 39.
The alleged attack happened on 11 January in The Drink nightclub in Guildford, where part-time law student Mrs Amogbokpa worked as a toilet attendant.
The singer, who was at Kingston Crown Court on Thursday for the first day of the trial, denies the charges.
Ms Tweedy, from Heaton in Newcastle, became caught up in a row after going to the club with fellow band member Nicola Roberts, the court heard.
The pair had been drinking champagne in the VIP area before going into the ladies' lavatory, where Miss Tweedy was seen to "stagger".
Patricia Lees, prosecuting, said the argument started after Ms Roberts asked her friend to pay for some lollipops and gum she had taken from Mrs Amogbokpa.
Mrs Amogbokpa, giving evidence, said: "When I asked her [Ms Tweedy] for the money, she said 'my father owns this place, I'm going to deal with you, I'm not going to give you any money'.
"She was very aggressive and she acted violently towards me - she grabbed those things.
"She was screaming and talking. She said 'you black bitch' just over and over."
Mrs Amogbokpa said Ms Tweedy had hit her after the club's weekend manager Phillip White was called in by Miss Roberts to try to restrain the singer.
The blow caused her glasses to fly off, the complainant said.
Ms Lees told the jury of seven men and five women: "The blow caused an injury to Mrs Amogbokpa's left eye [causing a] black eye with obvious swelling and bruising."
Under cross-examination, Mrs Amogbokpa accepted that the word "black" did not appear in the original statement she made to police moments after the
But under constant questioning from defence counsel Richard Matthews, she maintained she did not know why it had not appeared and that the word was used
in the insult allegedly made by Tweedy.
The jury was shown photographs of Mrs Amogbokpa's injuries, taken four days after the alleged assault.
The court was told she suffered severe swelling and bruising that lasted for three months.
Mrs Amogbokpa, who was treated in hospital, told the court she was in pain for three to four weeks after the attack and could not hand her coursework in because she could not see properly.
The singer is one of five members of the girl band created from the TV show Pop Stars: The Rivals, who reached number one with their debut single Sound of the Underground last Christmas.
Ms Tweedy denies racially aggravated assault occasioning actual bodily harm and assault occasioning actual bodily harm.
The trial continues.