Masked men armed with a hammer threatened a middle-aged man in his Thornton Heath home.
Croydon Police today launched an appeal for witnesses following the aggravated burglary in Quadrant Road on February 13.
A spokesman said the 47-year-old victim had arrived at his home at 11.05pm and had gone upstairs to his room.
Minutes later two men burst in and threatened the man - demanding his mobile phone, money and house keys.
He handed over his phone and keys and the men fled.
Detective Andy Pike, who is investigating the case, said: "It appears that the suspects were already inside the address when the victim returned home, having probably entered through the back patio door, which was smashed. We would urge anyone in the area who may have witnessed the incident or who may have seen anyone acting suspiciously in the area to contact us immediately."
A woman in her 80s was also in the house at the time of the burglary, although it is believed that she remained asleep during the incident and was not disturbed.
The two suspects are described as black men, both in their early twenties and approximately 5ft 8ins tall. One suspect was said to have been wearing a black scarf over his face, with a black hooded-top and black trousers. The second suspect was said to be wearing a black puffa jacket, a black scarf and black trousers.
Anyone who witnessed the incident or with information can contact Croydon police on 101 or Crimestoppers anonymously on 0800 555 111.