Bashir, 65, spent four weeks in Meyerton honing the skills of the 26-year-old boxer in preparation for his fight against Ghanaian Paakwesi "The Volcano" Ankrah.
Bashir has gone back home and will only be back next month.
"I have been in boxing for 45 years. When I say a boxer has potential, I mean just that. When I look at the top 10 in the heavyweights currently, I see that Ruann is in a favourable position of becoming world champion," Bashir told Sowetan before his departure.
Bashir's assistant, Soon Botes, will man Visser's corner against Ankrah at the Civic Centre in Kempton Park on March 31.
Visser's eight-rounder against Ankrah will form part of Xaba Promotions and Events box-and-dine tournament which, according to promoter Ayanda Matiti, will be part of Human Rights Month celebrations.
Visser, currently rated No 1, demolished Nhlakanipho Gwamanda in two rounds in December in Benoni.
The outcome was Visser's eighth knockout in nine wins. He has lost one fight.
Ankrah has chalked up 10 knockouts in 10 wins from 15 fights.
Topping Matiti's tournament will be IBO bantamweight holder Gideon "Hardcore" Buthelezi against Angel Aviles from Mexico.
Buthelezi, trained by Elias "Mr Fantastic" Tshabalala, will make the second defence of the belt he won in 2015.
Alfonzo Tissen and Xolani Mvubu will fight for the vacant ABU belt, while Sihle Jelwana will defend his No 1 spot in the junior bantamweight division against fourth-rated Athenkosi Dumezweni.
Nkosinathi Ntshangase will face Prince Ndlovu in the lightweight class.