Mathare United served Gor Mahia their first defeat of the season in the Kenya Premier League, following a 1-0 win on Wednesday afternoon at the Kenyatta Stadium, Machakos.
Gor started the match brightly, but it Mathare who carved out early chances, going close as early as the 13th-minute when a chance fell to captain Chris Oduor, who was unable to put the ball in the back of the net after the Gor keeper had misjudged a cross on the right from Martin Ongori.
David Owino came close to breaking the deadlock twice, and Clifford Alwanga too was culpable of a missed chance.
David Mapigano was called into action in the 30th minute, denying David Owino from close range.
Francis Afriye thought he had given Gor the lead in the 40th minute, but his effort was ruled out for offside.
On the stroke of half-time, the defending champions should have taken the lead, but Afriye's effort was cleared off the line by Owino as they dominated the last minutes of the half.
Both teams traded blows in the second half as the tie became an end to end contest, even though none of them could find the elusive goal.
In the 68th minute, James Kinyanjui thought he had finally given his side the lead, but his effort was ruled out for offside.
With the match seemingly headed for a draw, Daniel Otieno rose highest to power a header past Mapigano from a Kevin Kimani's perfectly weighted corner kick to give the Slum Boys the lead on the 89th minute.
Gor could not level as they suffered their first defeat of the season.
Western Stima 3-1 Bandari
Elsewhere, unbeaten Western Stima shocked Bandari with a 3-1 thrashing in a match that was played at the Moi Stadium Kisumu.
Bandari took the lead on the half-hour mark through Hassan Abdallah's header, beautifully meeting Fred Nkata's lovely cross.
The hosts grew into the match and levelled two minutes after the re-start following Nkata's handball in the box.
Samuel Odhiambo, the Western Stima keeper took the resultant penalty kick, finding the back of the net for a 1-1 scoreline.
It got worse for Mwalala's men two minutes later as Brian Otieno scored an own goal to hand the advantage back to the hosts.
Baron Oketch then completed a crazy six minutes with Stima's third of the afternoon. Bandari could not find an answer back, and they succumbed to their second defeat in a matter of days, having been bundled out of continental action.