The Bulls were made to work overtime for their 28-15 win over the Western Force in Perth on Saturday, which means the defending champs remain unbeaten in this year's Super 14.
The visitors outscored their hosts by three tries to nil, but never took a firm grip on the match thanks to the boot of James O'Connor who collected all of his side's points.
In fact, it was the Force who led 12-10 at half-time after O'Connor kicked a penalty to put the home side in front for the first time in the game. But an improved second-half display allowed the Bulls to grind out a victory and maintain pole position.
The final scoreline doesn't quite reflect the closeness of the match as Nathan Sharpe and his troops were still pushing the Bulls hard going into the final quarter, until Force centre Ryan Cross was sent to the sin-bin in the 64th minute.
That seemed to be the turning point of the match as the Bulls used the numbers to their advantage and scored eight points in ten minutes, while Cross could only look on helplessly.
The Force will take heart from the fact that they were able to deny the visitors a fourth try in the dying minutes, but the Bulls will realise that another inconsistent performance like this will be punished by the top teams.
Few gave the injury-ravaged bottom-placed Force any hope against the competition trendsetters, but the home side showed great resolve defensively. The biggest upset of the season loomed on the back of O'Connor's accurate boot, with five penalties from as many attempts.
The opening minutes of the game saw the confident Bulls camped inside the Force 22, determined to make an early statement as they searched for any defensive weaknesses.
In the ninth minute, number eight Pierre Spies - a great ball-carrier for the Bulls all night - spun around a Force tackle to cross on the tenth phase as the two-time Super Rugby champs went ahead 7-0.
It was a credit to the Force defence that the margin didn't blow out any further, as they repelled a steady stream of sustained Bulls attacks.
When the Force finally got their hands on the ball, they surprised the Bulls with their expansive play and with O'Connor in fine form with the boot, they launched a spirited and unexpected bid for victory.
When O'Connor kicked a penalty from a tight angle after the half-time hooter, the Force led the Bulls by two points at the break - a remarkable effort in this David versus Goliath clash.
That margin was extended to five points with another O'Connor penalty in the 49th minute, before the Bulls rallied as the Force tired.
Morne Steyn, who scored 18 points, made up for a couple of uncharacteristic penalty misses with a fine solo try to level the scores in the 57th minute and his subsequent conversion put the Bulls in front.
Another Steyn penalty extended the margin to five points, before the Bulls capitalised on the Force being down to 14 men after Cross was sent off, with Zane Kirchner crossing for an easy try to all but seal the result.
Man of the match: Force captain and lock Nathan Sharpe led from the front as always, but it was Pierre Spies who bashed his way to the front as always with trademark runs that kept the Bulls going forward when it mattered.
For Western Force:
Pens: O'Connor 5
Tries: Spies, Steyn, Kirchner
Cons: Steyn 2
Pens: Steyn 3
Force: 15 Mark Bartholomeusz, 14 Scott Staniforth, 13 Ryan Cross, 12 James O'Connor, 11 Mitch Inman, 10 David Hill, 9 Chris O'Young, 8 Richard Stanford, 7 Matt Hodgson, 6 Ben McCalman, 5 Nathan Sharpe (c), 4 Tom Hockings, 3 Tim Fairbrother, 2 Ben Whittaker, 1 Nic Henderson.
Replacements: 16 Pek Cowan, 17 Kieran Longbottom, 18 Luke Jones, 19 Ted Postal, 20 Mark Swanepoel, 21 Sam Harris, 22 Haig Sare.
Bulls: 15 Zane Kirchner, 14 Gerhard van den Heever, 13 Jaco Pretorius, 12 Wynand Olivier, 11 Francois Hougaard, 10 Mornè Steyn, 9 Fourie du Preez, 8 Pierre Spies, 7 Dewald Potgieter, 6 Deon Stegmann, 5 Victor Matfield, 4 Danie Rossouw, 3 Werner Kruger, 2 Gary Botha, 1 Gurthrö Steenkamp.
Replacements: 16 Bandise Maku, 17 Bees Roux, 18 Flip van der Merwe, 19 Derick Kuün, 20 Jacques-Louis Potgieter, 21 Jaco van der Westhuyzen, 22 Pedrie Wannenburg.
Referee: Nathan Pearce (Australia)
Assistant referees: Steve Walsh (Australia), Damian Mitchelmore (Australia)
TMO: Steve Leszczynski (Australia)