Vipers SC condemned Ugandan Premier League leaders Police FC to a 3-2 defeat at St Mary's Stadium in Kitende on Friday.
Ibrahim Orit scored twice while Ceasar Manzoki added the other goal as the Cops registered their goals from Erick Ssenjobe and Brian Mululi.
Police goalkeeper Derrick Ochan denied Vipers' Muhamad Shaban in the 15th minute in what was the most open chance for the hosts.
Shaban got a way past the Police backline but the Cops were saved by their custodian who came off better in the one-on-one situation.
The Venoms opened the score in the 21st minute when Orit collected a good pass from Disan Galiwango and fired past Ochan.