According to Amakhosi's physiotherapy David Milner, Mathoho suffered a concussion during the team's 2-0 defeat to Platinum Stars last week.
Xulu joined the medical room with a groin strain, and will therefore not recover on time for the encounter at the FNB Stadium.
“Tower suffered a concussion during the fixture against Platinum Stars last week,” Milner told the club's website.
“We observed him after the collision,” continued Milner. “We gave him a few minutes in the second half but had to substitute him as a precaution,” he explained.
The absence of the two centre-backs could forced Komphela to play Lorenzo Gordinho and Daniel Cardoso at the heart of the Amakhosi defence.
Meanwhile, Sibusiso Khumalo returned to training on Monday, only to limp off the training ground with a recurring knee injury.
The left-back has been sidelined for the over four weeks now, and will have to watch his teammates from the stands against the Clever Boys.
“Sbu is still struggling with his knee injury,” confirmed Milner. “We will continue to assess him, but he will not take part in the Wits game on Saturday,” said Milner.
The club also revealed that goalkeeper Brilliant Khuzwayo is making good progress as he continues recover from an ankle injury.
“We are happy with Khuzwayo’s progress to full fitness,” said the Amakhosi physiotherapy.