Sundowns beat Togo-Port 2-1 at Lucas Moripe Stadium, with Sirino scoring and providing the assist for Sibusiso Vilakazi's second goal for the Brazilians in Tshwane.
The victory revived Downs' hopes of advancing to the quarter-finals of the continental event, having lost their previous match to the Togolese side in Lome and drawn twice in Group C to pace-setting champions Wydad Casablanca and Horoya.
"I have been waiting for this kind of performance. It is kind of his game," said Mosimane of Sirino, who joined Masandawana in January from Bolivian outfit Bolivar.
"He came out of the shell and turned it on from the first minute. He was busy in the first half on the other side. He is getting his confidence and adjusting to the way we play."
'Jingles' believes Sirino is capable of carrying the team following the recent departure of star duo Khama Billiat and Percy Tau to Kaizer Chiefs and Brighton & Hove Albion respectively.
"Tonight (Friday) he carried the team probably because the other two players are not around. I have been waiting for someone to carry the team when Khama and Percy are not around. Normally it's Percy who turns the volume up most of the time. I am happy that he also scored."