At around 3.10pm on Monday 30 June a man in his 50s was walking towards the Central Line escalators when another man walked past him and began swearing.
A verbal disagreement began and escalated into a physical altercation at the bottom of the escalators.
The man was placed into a headlock and lost consciousness before the other man fled the scene and boarded a Central Line train.
Officers believe the man in the image may have information that could help their enquiries.
Anyone who recognises the man or witnessed the incident should text officers on 61016 using the reference 391 of 30 June.
Information can be given anonymously to Crimestoppers on 0800 555 111.