Western Province made it four wins from four this season as they edged the Blue Bulls 23-18 on Saturday.
The result leaves the men from Cape Town three points clear at the top - the Golden Lions beating the EP Kings in the late game - as they go into Round 5 at home to the Kings with confidence.
The Blue Bulls meanwhile pick up a losing bonus which puts them on five points after four games, something that will not please their supporters.
In a physically dominated opening half, just a 35th minute penalty from Kurt Coleman troubled the scorers as Western Province went in ahead.
However, both sides would have felt it could have been very different as young Blue Bulls fly-half Joshua Stander's easy penalty miss three minutes before the break was followed up by Western Province scrum-half Nic Groom losing the ball whilst looking to ground from an opportunistic dive one metre out.
Bloodied Catrakilis doubled Western Province's advantage six minutes after the interval thanks to a simple three points off the tee, as the Blue Bulls needed a response and fast.
It came almost immediately courtesy of a long-range score that saw Jesse Kriel feed Sampie Mastriet down the left wing before recycled ball found Jacques du Plessis, whose power and pace saw him over. Stander's simple extras pushed the hosts into the lead.
That proved to be the last act of Stander however, as Tiaan Schoeman replaced the Blue Bulls fly-half and he was on the scoreboard five minutes later to make it a 6-10 turnaround.
Frans Ludeke's side's four-point lead was short-lived though as the score of the game soon followed, with a backline set move seeing Seabelo Senatla feed Kobus van Wyk who raced over down the touchline. Catrakilis added the two points as Province went 13-10 ahead.
But Sevens finisher Senatla wasn't done there and on the hour mark turned from provider to scorer as his individual effort turned the game very much in favour of the visitors. At 20-10 the Blue Bulls needed to regroup if they were to avoid their third loss of the 2014 campaign.
That they did as a period of sustained pressure on the Province try-line led to Schoeman cutting the lead down to seven on 69 minutes, which was chalked off by a Coleman effort before Mastriet powered over on the left, making it 23-18 with under three minutes to go.
And that was how things stayed as WP, despite a late onslaught from the hosts, held on.
For Blue Bulls:
Tries: Du Plessis, Mastriet
Pen: Schoeman 2
For Western Province:
Tries: Van Wyk, Senatla
Con: Catrakilis 2
Pen: Coleman 2, Catrakilis
Blue Bulls: 15 Jesse Kriel, 14 Akona Ndungane, 13 William Small-Smith, 12 Burger Odendaal, 11 Sampie Mastriet, 10 Joshua Stander, 9 Piet van Zyl, 8 Jono Ross, 7 Jacques du Plessis, 6 Deon Stegmann (c), 5 Grant Hattingh, 4 Paul Willemse, 3 Werner Kruger, 2 Callie Visagie, 1 Dean Greyling.
Replacements: 16 Bongi Mbonambi, 17 Hencus van Wyk, 18 Nicolaas Janse van Rensburg, 19 Jacques Engelbrecht, 20 Rudy Paige, 21 Tian Schoeman, 22 Ryan Nell.
Western Province: 15 Cheslin Kolbe, 14 Kobus van Wyk, 13 Juan de Jongh (capt), 12 Jaco Taute, 11 Seabelo Senatla, 10 Demetri Catrakilis, 9 Nic Groom, 8 Nizaam Carr, 7 Michael Rhodes, 6 Siya Kolisi, 5 Manuel Carizza, 4 Jean Kleyn, 3 Pat Cilliers, 2 Stephan Coetzee, 1 Alistair Vermaak.
Replacements: 16 Neil Rautenbach, 17 Brok Harris, 18 Ruan Botha, 19 Rynhardt Elstadt, 20 Louis Schreuder, 21 Kurt Coleman, 22 Pat Howard.
Referee: Craig Joubert
Assistant referees: Rasta Rasivhenge, Cobus Wessels
Television match official: Willie Vos