Colombian Castro joined Kaizer Chiefs in January, while Billiat made the move to Naturena after his contract with Sundowns expired at the end of June.
Both players were key to Sundowns' success in 2015/16, when the club won the Absa Premiership and the CAF Champions League. Now Sundowns will come face-to-face with the duo at FNB Stadium on Saturday.
“You’ll see former teammates coming up against us, like Khama and Castro. It’s a crucial game for them, but we are ready for it,” said Ngcongca.
Ngcongca feels it’s important to get a victory over Amakhosi to get some confidence before their CAF Champions League rematch with AS Togo-Port.
Sundowns were beaten 1-0 by Togo-Port in a Group C match in Lome on Tuesday and will host the West Africans in Tshwane next Friday, a game they cannot afford to lose if they want to get to the knockout stages of the continental competition.
“It [the Shell Helix Cup] is an important game for us to show the character, and how we bounce back from a loss against Togo-Port. It will test our character and it’s a good opportunity for our new players to show our supporters what they can do.
“It’s going to be a nice game for both teams. You know at Sundowns we always play to win, so we will make sure that we win it for the supporters. We want to have our hands first on that trophy. At Sundowns there is a mentality of winning.”