The Chiefs surged to the top of the Super Rugby ladder on Friday after a late try saw off the the Bulls 28-22 in Hamilton.
The Chiefs scored three tries to one in a tightly contested match in which the lead changed six times, coming back from a lacklustre first half to outscore the Bulls 20-6 after the break.
The Bulls' rolling maul and Morne Steyn's boot kept the dogged South Africans within touching distance but a Sam Cane try 10 minutes from time proved decisive.
"We're thrilled that we could kick on in a very tight game," Chiefs captain Craig Clarke said.
"We didn't want to play a controlled, structured sort of game, that's more their style, we wanted to up the tempo a little bit."
The loss cost the Bulls a chance of overhauling the Western Stormers in the South African conference and their arch-rivals can draw level with the Chiefs in the overall standings with a win over the Coastal Sharks on Sunday.
Skipper Pierre Spies said that while he regarded two wins on the Bulls' four-match tour as a good return, he was frustrated Friday's match slipped away.
"They put us under pressure at the breakdown and we couldn't get our game going, then they got that try," he said.
"We thought we had a chance but that try made it very difficult for us."
The opening stages were fast-moving but mistake-ridden, with the scores locked on 3-3 after a penalty apiece after 15 minutes as defence dominated.
The Bulls' renowned forward pack twice threatened to set up tries through rolling mauls but could not break through and Steyn eventually settled for a drop goal on 22 minutes.
The Chiefs hit back against the run of play when Akona Ndungane spilled a speculative Aaron Cruden kick and opened the way for Andrew Horrell to soccer the ball over the line then touch down for a try.
Cruden tried the same tactic five minutes later but the Bulls' defence was alive to the danger and the South Africans again built pressure through the forwards, earning a penalty which Steyn kicked from 45 metres out.
Winger Bjorn Basson scored his eighth try of the season from the back of a Bulls' maul just before half time, outpacing Lelia Masaga for the five-pointer with Steyn adding the conversion to make it 16-8 at the break.
The Chiefs lifted after the restart, narrowing the gap to 14-19 as they notched two penalties to one, then taking the lead after Asaeli Tikoirotuma crossed with a slick move from a set piece off the scrum.
But the Chiefs immediately surrendered the advantage with a soft penalty, gifting Steyn his fourth penalty to make it 22-21.
The New Zealanders continued to run the ball and Cane brought the home crowd to life 10 minutes from time, latching onto a Sonny Bill Williams offload for the Chiefs' third try.
A Cruden penalty extended the lead to 28-22 and the Bulls could not break through before the clock ran down.
CHIEFS 28 (Sam Cane, Andrew Horrell, Aseli Tikoirotuma tries Aaron Cruden 2 cons 3 pens) bt BULLS 22 (Bjorn Basson try Morne Steyn con 4 pens drop goal) at Waikato Stadium. Referee: Mark Lawrence.