The Bulls' bulk and grunt proved too much for the craft and guile of the Sunwolves as the South Africans claimed a 30-27 in Singapore on Saturday to leave the new Japanese franchise still searching for a first win.
Bulls skipper Adriaan Strauss, flanker Roelof Smith and winger Jamba Ulengo barged over for the tries at the National Stadium as the three-times champions picked up their second win from four matches this term.
The three-point victory was the least the South Africans could have managed such was their domination of possession and territory against a side clearly lacking the physicality of their opponents.
What the Sunwolves do have, though, is pace and ingenuity.
A kick over the top of a slow-turning Bulls defence resulted in a try within 90 seconds for the Japanese when flanker Andrew Durutalo profited from Burger Odendaal's fumble to touch down.
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Tusi Pisi converted and added another penalty but the Bulls only trailed 10-9 with flyhalf Tiaan Schoeman knocking over three three-pointers.
Sunwolves Argentine number eight Tomas Leonardi was sent to the sin bin in the 21st minute for hands in the ruck on his own line and the Pretoria-based side took advantage of the extra man with hooker Strauss scoring from a catch and drive maul.
Bulls blindside Smit grabbed a second try from a similar move at the start of the second period, with Schoeman converting to stretch the lead to 23-10 as the visitors seemed set to run away with the contest.
The plucky Sunwolves refused to buckle, though. Pisi slotted another penalty and the Samoan was instrumental in a brilliant move starting deep in their own half which went through several hands before Akihito Yamada crossed in the corner.
Pisi converted and fullback Riaan Viljoen came within inches of drawing the hosts level, only to see his 60th-minute penalty from his own half hit the right-hand upright.
The warning fired the Bulls back into gear and Ulengo was adjudged by the television official to have touched down against the post six minutes later for a third try after several phases of pressure deep in the Sunwolves 22.
The Sunwolves, though, battled on and a brilliant lineout move saw second row Liaki Moli drop the ball down for replacement Yuki Yatomi to dart through the broken Bulls line and grab a try and losing bonus point after the buzzer.
