The Bulls set up a visit to tackle the seven-time champion Crusaders in next week's knockout stages after defeating the Lions 37-20 at Loftus.
Had they avoided picking up the try bonus-point, the Bulls would have instead gone to Brisbane to face the Reds, who are facing the prospect of not having mercurial pivot Quade Cooper after he was cited for a dangerous tackle earlier in the day.
But they chose to go all-out in their clash with their South African neighbours and ultimately set up what is a mouth-watering clash in Christchurch.
In next week's other game, the Reds host the Sharks. The Stormers and Chiefs have a bye.
The visitors played with heart in their last game of the season, and were level at half-time, but a strong second-half secured victory for the hosts.
Elton Jantjies drew first blood with a penalty but the Bulls replied afterwards with one of their own from Mornè Steyn, who is top of the points table.
The tide turned in the Bulls' favour when winger Akona Ndungane intercepted a floating pass from Jantjies to score the first try of the game after sixteen minutes of play, with Steyn converting.
Jantjies shortened the deficit eight minutes later with a penalty conversion, but Bulls winger Bjorn Basson extended the lead after half an hour, scoring his tenth try of the season.
Francois Hougaard made a run from a scrum in the Lions' 22, pulled in two defenders and offloaded to a speeding Basson, who scored under the posts, with Steyn converting.
Lions scrum-half Michael Bondesio hit back five minutes later though when he also picked the ball up from the back of a scrum to break to his right, dummy and score under the posts.
Jantjies converted to bring his side within four points of the Bulls, while Steyn succeeded with a penalty conversion with only two minutes left in the second half to make it 20-13.
The visitors' dogged determination saw them cross the whitewash on the half-time whistle, with a beardless Joshua Strauss scoring from a driving maul after a successful line-out five metres from the line. Jantjies converted to level the scores at 20-20 going into the break.
The Bulls hit their straps in the second period, adding two more tries to take the match away from the visitors. Hougaard scored the Bulls' third try shortly after the restart with an enterprising run from a ruck on the Lions' 22-metre line, with Steyn converting.
Five minutes later flanker Jacques Potgieter secured the bonus point. Steyn converted and added another three points with a successful penalty with fifteen minutes left in the match.
The Bulls fended off the spirited Lions to keep the scores unchanged in the dying stages.
Tries: Ndungane, Basson, Hougaard, J Potgieter
Con: Steyn 4
Pen: Steyn 3
Tries: Bondesio, Strauss
Con: Jantjies 2
Pen: Jantjies 2
Bulls: 15 Zane Kirchner, 14 Akona Ndungane, 13 JJ Engelbrecht, 12 Wynand Olivier, 11 Bjorn Basson, 10 Morne Steyn, 9 Francois Hougaard, 8 Pierre Spies (c), 7 Jacques Potgieter, 6 Dewald Potgieter, 5 Juandrè Kruger, 4 Wilhelm Steenkamp, 3 Werner Kruger, 2 Chiliboy Ralepelle, 1 Dean Greyling.
Replacements: 16 Willie Wepener, 17 Frik Kirsten, 18 Deon Stegmann, 19 CJ Stander, 20 Jano Vermaak, 21 Louis Fouchè, 22 Francois Venter.
Lions: 15 James Kamana, 14 Lionel Mapoe, 13 Waylon Murray, 12 Butch James, 11 Anthony Volmink, 10 Elton Jantjies, 9 Michael Bondesio, 8 Joshua Strauss (capt), 7 Grant Hattingh, 6 Derick Minnie, 5 Ruan Botha, 4 Hendrik Roodt, 3 Jacobie Adriaanse, 2 Callie Visagie, 1 JC Janse van Rensburg.
Replacements: 16 Martin Bezuidenhout, 17 Ruan Dreyer, 18 Etienne Oosthuizen, 19 Jaco Kriel, 20 Ross Cronje, 21 JR Esterhuizen, 22 Ruan Combrinck.
Referee: Craig Joubert (South Africa)
Assistant referees: Sindile Mayende (South Africa), Stefan Breytenbach (South Africa)
Television match official: JC Fortuin (South Africa)