UJ beat local rivals Wits 39-16 for their first victory of the season, while there were also Varsity Cup wins for Tuks, Shimlas and Maties on Monday.
UJ came into this fixture under pressure, having lost all four of their matches and sitting second from bottom on the table.
Wits were favoured to give their playoff hopes a boost as they looked to recover from two defeats.
The visitors got themselves briefly back into the game after falling 17-0 behind at the break when Adriaan van Blerk and Daniel Kapepula went over in the second half.
However, a brace from fullback Odwa Nkunjana, to go with a fine individual showing from Man of the Match Jack Hart, saw UJ stun their neighbours.
In the first of two non-televised matches, Shimlas boosted their playoff hopes by withstanding a late comeback from UCT to win 51-40 in Bloemfontein.
Two tries from Ruan Henning to go with a seven-pointer from Cham Zondeki and a five-pointer from Marnus Boshoff put the home side in a commanding position at half-time, before Ikeys fought back late in the second half to come away with a four-try bonus point.
Meanwhile, Tuks piled more misery on newcomers UWC by claiming a 70-12 victory in Cape Town that saw them keep up with table-toppers Maties.
Later in the day, a hat-trick from Maties wing Edwill van der Merwe saw the defending champions beat challengers NWU 43-15 in Stellenbosch.
Round five results:
UJ (39) – Tries: Odwa Nkunjana (2), Shaun Williams (seven-pointer), Adrian Bester. Conversion: Mashudu Raphunga (3). Penalties: Raphunga (3)
Wits (16) – Tries: Adrian Van Blerk. Kasende Kapepula (seven-pointer). Conversions: Ruan Cloete (2)
Shimlas (51) – Tries: Cham Zondeki, Ruan Henning (2) Marnus Boshoff (2) Zak Burger, Tiaan Schutte. Conversions: Lubabalo Dobela (5). Penalty: Dobela.
UCT (40) – Tries: Cornelius Otto, Darian Hock, James Tedder(2), Cuan Hablutzel, Gary Porter. Conversions: Lohan Lubbe (1), Darian Hock (4). Penalty: Lubbe.
UWC (12) – Try: Tristan Leyds (seven-pointer). Conversion: Keagan Fortune. Penalty: Fortune.
Tuks (70) – Tries: Theo Maree, Johan Grobbelaar, Johan Grobbelaar, Stephan Smit, Marius Verwey, Ruan Nortje, Ciaran Dayara, Irvin Ali, Hanru Sirgel, Jacobus Eloff. Conversions: Tinus de Beer (10)
Maties (43) – Tries: HJ Luus, Edwill van der Merwe (2×7 pointers; 1×5 pointer), Dan Jooste. Conversions: Jordan Chait (3), Reinhardt Fortuin. Penalties: Chait (3).
NWU (15) – Tries: Gideon van der Westhuizen; Wian Conradie. Conversion: Schalk Hugo. Penalty: Hugo.
Photo: Dominic Barnardt/Varsity Sports