London, July 23 - Troubled British singer Amy Winehouse left a female fan numb when she punched her in the face as the woman posed for a photo with the star.

The singer, who recently returned to Britain following an extended holiday in the Caribbean, arrived at London's City of Westminster Magistrates' Court Thursday morning to stand trial for allegedly assaulting dancer Sherene Flash, reports contacmtusic.com.

Flash took the stand and told the hearing that Winehouse lashed out at the End of Summer Ball in the British capital last September. She had been dancing at the venue that evening and later saw Winehouse looking 'drunk and like she was on drugs' in a dressing room. Flash and a friend approached the singer and asked for a photograph and as they posed with Winehouse, the star allegedly hit her in the face.

Flash told the court: 'She punched me forcefully in my right eye. I started to cry and I was shocked.'

Lawyers for Winehouse insist the singer accidentally 'caught her in her eye' as she tried to push Flash away.

Winehouse, 25, has pleaded not guilty to the charge and is expected to take the stand herself during the trial, which is scheduled to last two days.