The first match for the tactician will be on Wednesday against former team KCB on Wednesday
Former Gor Mahia assistant coach Frank Ouna is set to take over at Mathare United after the sacking of Salim Ali.
The Slum Boys management opted to make the changes in their bid to save the team from relegation in the ongoing Football Kenya Federation Premier League campaign.
The 2008 league champions have been struggling to get positive results consistently since the start of the campaign. They started the league late after tussles with the federation regarding the broadcasting rights before being reinstated later on.
However, the tactician has failed to steady the ship.
"It was a tough decision but we have eventually decided to let Salim go because of the poor results we have been having," Mathare United CEO Jectone Obure told Goal.
"We had to make some changes to see if we can turn the results around. Ouna is a great coach, we believe he will help us get off the bottom and help the team survive relegation."
When reached for comment, the axed tactician revealed it was easy working at the club.
"Pushing demoralized players to give their best in matches has not been easy," Salim said.
"Players have gone for months without pay and there are some issues as well that make it hard for the team to deliver. I wish whoever coming in the best since everybody wants to see the team remain at the top. But more is needed."
Prior to his sacking, the former Ulinzi Stars tactician had led the team in 14 matches where he managed one win, four draws, and nine losses. The latest assignment was against Vihiga United where they managed a goalless draw.
"Though small, the draw is a step in the right direction," the former player said afterwards.
"I said before the game that we consider it a new campaign and that we will not dwell on what happened prior to the two-month break. So we take the point and now turn our attention towards our next assignment.
"I saw plenty of positives against Vihiga, one of which was the fighting spirit and I want to foster that as, without it, you are dead before a ball is kicked."
Ouna's first assignment will be on Wednesday against his former team KCB.