Maties got revenge for their defeat in last year's Varsity Cup Final with a late 18-16 victory over UP-Tuks in Pretoria on Monday.
The dramatic win sees the team from Stellenbosch retain their spot at the top of the standings as the only unbeaten team in the competition, but they were pushed to the limit by a physical UP-Tuks outfit.
The teams were deadlocked at 16-16 at halftime, which is how it stayed until a late penalty from replacement flyhalf Dean Grant sealed the victory for the visitors.
It was the second defeat this season for defending champions UP-Tuks after their opening round defeat to NWU-Pukke in Potchefstroom, and they have sunk to fourth position on the standings behind Maties, UJ and NWU-Pukke after four weeks of action.
UJ secured their spot behind log-leaders Maties with a resounding 63-24 victory over local rivals Wits in the first-ever Varsity Cup Johannesburg derby.
Fullback Kobus de Kock ran in a remarkable four tries as UJ showed the Varsity Cup newcomers what life at the top is all about, notching nine tries in all in their dominant performance.
NWU-Pukke continued their winning ways when they held off a desperate UCT side to record a tight 29-26 victory in Potchefstroom.
The defeat leaves the Ikeys still searching for their first win of the season, although they did take two bonus points away from another frustratingly close loss.
In Port Elizabeth, the NMMU Madibaz secured a morale-boosting 14-10 win over UFS-Shimlas in another match that went right down to the wire.
Two late penalties from flyhalf Justin van Staden sealed the Madibaz's second home win of the season, but they had to come from behind having trailed 8-10 at the second strategy break
The defeat was UFS-Shimlas' third loss in a row, and leaves coach Michael Horak's team searching for some inspiration in the second half of the season.
In the Varsity Shield the TUT Vikings secured their first win of the competition when they beat Peter de Villiers's UWC side by 18-8 in Pretoria.
UKZN returned to winning ways with a tight 20-18 victory over a committed Fort Hare side that pushed them all the way in Alice - a rare defeat at home for the combative Blues.
In the Varsity Young Guns competition, NWU-Pukke got their campaign off to a flying start with a resounding 60-8 victory over newcomers Wits in Potchefstroom, whilst the Maties juniors were forced to work hard for their 34-24 victory over NMMU in Port Elizabeth.
In the Steinhoff Koshuisrugby Championships, Wits side Steinhoff Commerce continued their tough introduction to the competition when they went down 69-10 to UJ outfit Bastion.
In Potchefstroom, finally, NWU-Pukke koshuis Villagers got their season off to a solid start with a 24-5 win over NMMU outfit Northernz. In Pretoria, Steinhoff Medies (from Stellenbosch) gave a taste of what was to come in the main game when they beat UP-Tuks side Mopanie by 28-24.