Mathare United recorded their ninth Football Kenya Federation Premier League loss after going down 2-1 to Kariobangi Sharks on Thursday at Kasarani.
A double from Peter Lwasa was enough to hand the visitors the victory as Khalid Juma, who came on in the second half, struck to deny them a clean sheet.
Kariobangi Sharks took the lead in the 10th minute when a shot by Lwasa deflected off an opponent and found its way into the net. The Slum Boys almost equalised in the 13th minute when Danson Kago, after collecting Norman Ogolla's cross, forced goalkeeper Brian Obiero into a fine save.
Obiero, who is continuing to have good times since making his Kariobangi Sharks debut, made two quick saves in the 19th minute to deny Mathare's Lennox Ogutu and David Ochieng.
Kariobangi Sharks almost doubled the lead in the 25th minute when top scorer Erick Kapaito collected a poor clearance by Mathare's backline but his effort was stopped by the woodwork.
Lwasa, however, added the second goal for the visitors a minute past the half-hour mark with a low drive to punish a rather disjointed Slum Boys.
In the 52nd minute, Ochieng's free-kick flew just above the crossbar as Mathare United made their first attack of the second half.
William Muluya made a change in the 54th minute as he introduced Shaphan Oyugi for Lwasa. On his part, Mathare's Salim Ali brought on Daniel Otieno and Boniface Akenga for John Mwangi and Tyson Otieno in the 58th minute.
Four minutes past the hour mark, Ogutu nearly gave Mathare United a goal but he was denied by the crossbar. They were also unfortunate to see Dani Lual's strike hit the woodwork in the 70th minute as they surged forward looking for goals. Ali handed Anthony Otieno his debut in the 71st minute when he replaced Martin Ongori.
Akenga was withdrawn in the 80th minute for Khalid Juma who pulled one back for the home five minutes later.
The next two games for Ali's side will be against Posta Rangers and KCB while Kariobangi Sharks will be up against Ulinzi Stars and Nairobi City Stars.