An 18-year-old man was grabbed round the neck during an "unprovoked assault" by two men in a park in Surrey.
Surrey Police said the teenager was also threatened and had his wallet containing £90 taken during the attack near Caselden Close, Addlestone.
Detectives carried out house-to-house inquiries following the incident at about 1340 GMT on Monday.
Officers said one of the suspects had a distinctive wolf or dog tattoo on his hand. They have appealed for witnesses.
Det Con Chris Ewan said: "This was an unprovoked attack on a young victim which took place in broad daylight.
"Fortunately the victim was not injured during the robbery but I feel certain that people living in the Addlestone area hold the key to finding those responsible."