Tau was named Man of the Match after replacing striker Leonardo Castro in the first half against Matsatsantsa at Loftus Versfeld Stadium on Sunday.
Castro injured his ankle, ruling him out of his club's CAF Champions League semi-final with Zesco United in Zambia on September 17.
"We had to work hard for the result because we lost an important player in Castro," said Tau.
"It is important to have a strong bench and thanks to the coach and the technical team in preparing for this game. We knew which side to attack and how to defend when we lose the ball. It was a collective victory and we are happy that we progressed to the semi-finals."
Tau is back with the Brazilians after spending last season on loan to National First Division side Witbank Spurs. The Mpumalanga-born midfielder says his relationship is growing with Mosimane.
"I do a lot of talks with the coach. He is always behind everything I do. We are building a strong bond because he is starting to understand more of what I am trying to do, and also I am trying to understand his tactics and how to be in the structure of the team."
Downs will meet Chippa United in the next round of the MTN8 over two legs, while Cape Town City will tackle Bidvest Wits on the weekend of September 10/11.