Ugandan defender Shafic Batambuze missed his penalty in the shootouts as Gor Mahia was ousted of the Sports Pesa Cup.
Gor, having won the past two editions were strong favourites against a less known Tanzanian side Mbao FC ahead of the Wednesday tie.
The match ended in a one all draw before Mbao edged through 4-3 to reach the semis of the Sports Pesa Cup, where a winner gets a chance to face English Premier League side Everton FC.
Uganda’s Erisa Ssekisambu had his goal wrongly disallowed but Denis Oliech converted from the spot to put the Kenyan Giants in a deserved lead.
Mbao could later level matters through Abubakary Ngalema in with 15 minutes left on normal time, and the minnows held on to send the game into shootouts.
Gor missed two kicks – Haruna Shakava and Shafik Batambuze – as Mbao converted four while missing one.
Batambuze has played for Simba, Muhoroni Youth, SC Villa, Western Stima, Sofapaka, Tusker and Singida United.