The Brazilians were out to take advantage of Orlando Pirates' slip-up in midweek, and their start showed they were not keen on letting up.
An exciting move by Percy Tau and Zwane played in Vilakazi at the back-post and the former Wits man almost found the opener but Darren Keet denied him with an outstretched save.
After being caught wanting the duration of the opening minutes, Downs finally got their reward with a cool composed finish by Zwane after Wits were caught in possession by Tau on 21 minutes, who played in his team-mate.
Wits were looking for an immediate response with Lehlohonolo Majoro going close following a pass from Daylon Claasen.
At the other end, Downs broke on a counterattack with Gaston Sirino, Zwane and Tau, and a poor clearance by Buhle Mkwanazi fell to Zwane, who beat one defender before being blocked from shooting at Keet by Edwin Gyimah.
Daine Klate looked to break their duck with a close shot after being played through by Phumlani Ntshangase, but Denis Onyango gathered it well.
With halftime on the horizon, Tau instigated the second with The Students caught napping yet again and Vilakazi broke on the right side to beat an on-rushing Keet with a low-drive to close the first stanza.
A double change by Gavin Hunt at the start of the second half saw Abednego Mosiathlaga and Granwald Scott making their entries as they looked for solidity in the middle of the park.
Downs brought about their first change after 58 minutes when Thapelo Morena replaced Vilakazi, with the game drifting at either end of the scale.
The former Bloemfontein Celtic man didn’t wait long to be in the thick of the action and, after beating the offside trap, he shot directly at Keet with Zwane and Tau shouting for service.
Captain Hlompho Kekana tried to catch Keet off guard from his own half, but the Cape Town-born shot-stopper was well positioned to make the save.
The visitors struggled to get back into the game as the half continued, with little to no impact from all areas of the field.
It thus ensured a rather easy close-out for the Brazilians as they get ever closer to the reclaiming the title they lost to the same Wits side last term.