A tourist broke his leg after being mowed down by a gang of moped riders who were attempting to steal his watch in central London.
The victim, in his 30s, was pursued by the group on Park Lane, in Westminster, at 3.10am on April 30.
The Metropolitan Police has released CCTV footage showing the man running away after he was surrounded by eight suspects on four mopeds - three of which mount the pavement as they pursue him.
He is seen escaping from the group but falls to the floor moments later after being struck by one of the vehicles.
The man was able to crawl away from his attackers, who rode off empty-handed, but he required treatment for a broken leg, Scotland Yard said.
Detective Constable Richard Kidd said: “This happened just after 3am when a group of four or possibly more mopeds riding together would have been conspicuous.
“I want to hear from anyone who recalls seeing such a group or who may have seen the mopeds being abandoned - or perhaps being stored in a lock-up or similar location - in the early hours of April 30.
“One of the mopeds would have sustained damage to its left side.”
Anyone with information should contact police on 101 or Crimestoppers anonymously.