Mahlambi, who was recruited from Egyptian giants Al-Ahly, marked his Sundowns debut with a goal in a drama-filled 3-3 draw with AmaZulu at King Zwelithini Stadium on Sunday.
The 21-year-old nudged Thapelo Nyongo off the ball in the 19th minute before beating his former Bidvest Wits teammate Moeneeb Josephs at the second time of asking after his initial effort was saved by the goalkeeper.
Mahlambi had another chance five minutes before the break as he chased down a long ball over the top, but Usuthu defender Mbongeni Gumede managed to clear the danger after recovering from a slip.
Mosimane believes Mahlambi will benefit under his tutelage at Chloorkop in similar fashion to Tau and Khama Billiat.
"He was supposed to score and that's why we have him here," Mosimane said of Mahlambi.
"He did well, first game, first goal, good.
"I think he should have scored the other one in the first half again. He allowed the defender to come from behind and take the ball from him.
"Good player, young, very, very raw. Very, very raw. He needs a lot of work and he reminds me of Percy Tau when he came. Even Khama Billiat, a lot of work.
"Spending a year or two with me, I think we are going to get a better product for South Africa."
Reigning PSL Footballer of the Season Tau traded Downs in August for English Premier League side Brighton & Hove Albion, while Billiat switched allegiance to rivals Kaizer Chiefs.