Girls Aloud singer Cheryl Tweedy hit a nightclub attendant with a "right hook", a court has been told.
Cheryl Tweedy was seen falling over while dancing, the court heard
Philip White, head of security at the nightclub, told Kingston Crown Court that the singer gave the toilet attendant a "right hook", which he identified from the boxing training he had done.
The court was also told that the singer made comments in the club's VIP area after the altercation with Miss Amogbokpa.
It is claimed she swore, called for Miss Amogbokpa to be brought up and said she would "finish the job".
'Called her a bitch'
Another witness to the row said the singer became hysterical and punched Sophie Amogbokpa in the face.
The court heard Miss Tweedy, from Heaton in Newcastle, appeared drunk and fell over on the dance floor.
Miss Tweedy, 20, denies racially aggravated assault occasioning actually bodily harm on 39-year-old Mrs Amogbokpa.
The alleged incident happened at The Drink club in Guildford, Surrey, on 11 January.
The court heard Miss Tweedy was in the club with her bandmate Nicola Roberts in the early hours of 11 January.
Witness Bryony Gibbs told the jury on Friday she thought Miss Tweedy was drunk and she had seen her fall over as she sent a text message on her mobile phone while dancing.
Miss Gibbs then said she saw the two singers in the club's upstairs toilets and saw an argument start just after 0100 BST.
She told the court Miss Tweedy used make-up and took some lollies from a display in the ladies' toilet without paying.
Miss Gibbs said: "The toilet attendant was saying to Cheryl 'I want payment for the lollipops' and Cheryl was saying 'I do not have to pay for the lollies'."
She then said Miss Tweedy swore at Mrs Amogbokpa and called her a "bitch".
'A bit scared'
Miss Gibbs said: "She (Miss Tweedy) seemed hysterical, she was just hysterical - shouting a lot and she was still drunk.
"She (Mrs Amogbokpa) kept on repeating 'I want payment for those lollies'.
"When the toilet attendant leaned forward to take away the lollies from Cheryl, Cheryl punched her."
The witness then said the singer's friend tried to calm her down, but she was still screaming and swearing.
Miss Gibbs added: "I was a bit scared, that is why I left."
Mrs Amogbokpa, who was treated in hospital, told the court on Thursday she was in pain for three to four weeks after the attack.
Miss Tweedy, is one of five members of the girl group created from the TV show Popstars: The Rivals.
The trial continues.