Gor Mahia ended KCB's un-beaten run with a 2-1 victory during a Tusker Premier League match at City Stadium on Sunday.
Donald Mosoti and Rama Salim were the scorers for Gor Mahia while Clifford Alwanga netted for the bankers.
Mosoti opened Gor's account at KCB with a 55th minute header after he was picked out by Moses Odhiambo from a free-kick.
But hardly had the celebrations died down in the Gor camp when Musa Mohammed handled inside his box to give the bankers a penalty which Alwanga easily converted in the 56th minute and sent his tally to six goals and remain the top scorer in the league.
Salim also scored through a penalty and it was at the stroke of full time when Dan Sserenkuma was brought down and the referee pointed to the spot.
It was the bankers, who showed early intention to win this match. They were comfortable on the ball and did well to deny Gor possession.
Alwanga blasted wide on two occasions in the first half from chances that should have opened the account for his side. First he found himself unmarked inside the Gor box but blasted wide when all he had to do was place the ball inside the net in the 13th minute.
Two minutes later, Alwanga once again found himself with acres of space to shoot from but he once again wasted the opportunity.
Alwanga's co-striker Jacob Keli forced Jerim Onyango in Gor's goal to make a save of the first half after he jumped to tip out the ball in the 20th minute.
But as the bankers failed to break the deadlock, Gor's confidence was soaring gradually. In the 30th minute, a combination between Rama Salim and Dam Sserenkuma nearly gave them the opener but the Ugandan missed to connect a brilliant effort by his partner.
The bankers ended the first half on a more positive note with Alwanga's effort going just wide.
However, real action was witnessed in the second half where all the three goals came and Gor will be glad to pickall three points at home.