Video of a 16-year-old girl being knocked unconscious in an unprovoked street attack has been released by police.
CCTV footage shows the assailant approach the victim from behind before punching her so hard she falls over, hitting the pavement face-first.
Police are appealing for information after the teenager was followed from her home by her attacker, who struck without warning outside the Black Lion pub in Plaistow High Street, east London.
Scotland Yard described the suspect as black and muscular, wearing a black baseball jacket and jeans, with a shaven head and aged between 25 and 30.
A Metropolitan police spokesperson said: "At about 12.30pm on November 13, a male suspect followed a 16-year-old girl from her home address for approximately 500 metres.
"When he was near the Black Lion public house, he ran up behind her and threw a punch to her head.
"This was an unprovoked attack. The victim fell to ground and was unconscious."
After the assault, the suspect turned around and jogged back towards Green Gate Street.
The girl was taken to hospital and released with cuts and bruises later that day.
:: Anyone with information should contact Newham Violent Crime Unit on 020 8217 5890 or Crimestoppers on 0800 555 111.