She asked her for a lighter and when the victim said she didn’t have one the attacker began punching her, pulling her hair and kicking her.
The woman, who managed to run away, was covered in bruises and scratches while clumps of her hair were also pulled out.
The incident happened about 11pm on Saturday 28 July – the Magic Numbers were playing at the venue that night.
Since then officers have carried out local enquiries including trawling through CCTV. The investigating officer has also circulated the image of the woman they want to speak to across the force.
However, despite these attempts to identify her, officers still don’t who she is and need to speak to her urgently.
PC Liz Ralph, from GMP’s Trafford borough, said:
“This was a vicious and brutal attack on an innocent woman as she stood outside the venue waiting for a friend.
“Although her physical injuries were not really serious, this attack shook her up and has made her understandably fearful.
“We are desperate to identify the woman pictured and I would urge anyone who recognises her to please call police.
“If this is you, then I would also ask that you make contact with officers at the earliest opportunity.”
Any information can be passed to police by calling 0161 856 7530 quoting incident number 558 of 1 August 2018 or the independent charity Crimestoppers, anonymously, on 0800 555 111.