Mthembu lead the line in Amakhosi's 1-1 draw with Celtic in the MTN8 semi-finals, notably earning a penalty and testing Man of the Match Patrick Tignyemb with a strike on the turn on Sunday.
Bernard Parker missed from the spot but made amends with a spectacular finish to cancel out Helder Pelembe's likewise stunning goal at Free State Stadium.
"Siphelele Mthembu played well today," Chiefs coach Komphela was quoted as saying on the club's website.
"He gave us what we needed."
Komphela added: "We are addressing the centre of defence. Erick Mathoho is still finding his feet after missing pre-season, but he has done well partnering with Xulu in central defence."
The former Maritzburg United boss believes his side can improve on their decision making in the final third.
"In terms of the strikeforce, Parker has been playing as our number 10.
"Our decision making process is not good enough in the third part of the pitch."