Much was expected from the attacking midfielder when he joined the Brazilians from Zimbabwean side Bantu Rovers in 2014.
Mahachi struggled to establish himself in his first season with the Tshwane giants - making only 13 appearances in the Premier Soccer League (PSL) during the 2014/15 campaign.
The Zimbabwe international was then shipped out to Lamontville Golden Arrows on loan from Sundowns ahead of the 2015/16 PSL season.
"I had fear when I joined Sundowns. I was very young from Zimbabwe. I had a lot of fear. I only got confidence at Arrows. That is where I got to express myself and to well," Mahachi was quoted saying on Power FM Sport.
"As a player, you can arrive at a team as a hot property. When you get to a new environment, you must adjust, you see? I had that fear at Sundowns," he continued.
"I had that fear because I was playing with top players like Surprise Moriri, Teko Modise, Anthony Laffor, Elias Pelembe, you can name them. I did not expect to play with them at that time," he explained.
"Playing with big guns like Moriri and Teko should have been motivation, but I did not believe in myself. I was young and I thought time was on my side. That was not the case because that is a big team with quality players," he said.
The left-footed player enjoyed his football at Abafana Bes'thende where he spent three seasons on loan from the Brazilians. His efforts attracted interest from Pirates, who signed him from Sundowns earlier this year.
"I really started expressing myself a lot more at Arrows. I can safely say Arrows is the team that made me. It is now an honour to join Pirates. I just wanna continue where I left off at Arrows last season," he added.
"I have matured now. I played three seasons at Arrows and I know how the PSL works. I want to do well at Pirates. Now I feel that I will do better here because coach Micho (Milutin Sredojevic) and coach Rhulani (Mokwena) believe in me," he concluded.
Pirates will kickoff their 2018/19 PSL campaign against Highlands Park at the Orlando Stadium in Johannesburg on Saturday.